Understanding Cancer Research Terms

Deep learning: Deep learning is a subset of machine learning. It's a family of machine-learning models based on layers of artificial neural networks, which can be a combination of hardware and software. Deep learning uses machine-learning techniques to solve real-world problems. It requires massive data sets to train machines to do what the brain does naturally. Deep-learning systems permit a machine to train itself and create new content—like images, text, or audio. In medicine, deep learning is used to classify skin cancer and identify diabetic retinopathy. See machine learning.

Diagnostic biomarkers: A biomarker used to help identify and diagnose conditions. High glucose levels are a diagnostic biomarker for diabetes.

Diploid/Diploidy: Ploidy refers to the number of chromosome pairs in a cell. Normal cells have 23 pairs, known as diploidy. See ploidy and aneuploidy.

DNA (deoxyribonucleic acid): The hereditary material, sometimes referred to as the genetic blueprint, in humans and almost all other organisms. DNA holds genetic information on cell growth, division, and function and is passed from one generation to the next. Nearly every cell in a person’s body has the same DNA.

Most DNA is located in the cell nucleus, but a small amount of DNA can also be found in the cell’s mitochondria. When cells divide, each new cell needs to have an exact copy of the DNA that was in the old cell.

DNA chains coil into 46 chromosomes, 23 from each parent. See also RNA.

Discovery research: Experiments with genes, cells, animals, or people to find a new or improved understanding of an action, health behavior, process, technique, technology, or model to improve care.

Disparity (see cancer disparity and health disparity)

Epidemiology: The study of the occurrence, distribution, and possible causes of diseases (like cancer) in a group of people.  

Epigenetic age/epigenetic aging (see biologic age)

Epigenetic changes (see epigenetics)

Epigenetic mark (see epigenetics)

Epigenetic signature (see epigenetics)

Epigenetics/epigenetic changes (also known as epigenetic marks or signatures): The study or process of how a person’s behaviors (like diet and exercise) and environment (like toxins, healthy or unhealthy stress management, and draining or inspiring school/work environments) can cause changes that add or remove special marks on a gene’s DNA that affect the way your genes work and how active they are. 

Epigenetic changes affect how your body reads a DNA sequence but doesn’t change the sequence as genetic changes do. Specifically, epigenetic changes, turn genes “on” and “off.” Different genes are more active in some cells than in others. Even within a certain cell, some genes are active at some times and inactive at others. Epigenetics has a strong influence on how a person develops and can alter individual traits.

Behaviors that may change epigenetic patterns/marks:

• Alcohol consumption
• Environmental pollutants
• Nutrition/diet
• Obesity
• Physical activity
• Psychological Stress
• Smoking
• Working habits (like working night shifts)

Some epigenetic changes increase your risk of developing cancer and other health conditions. It may be easier for scientists to find and remove bad epigenetic marks, though, compared to fixing a hardcopy genetic mutation. For example, reversing epigenetic changes may reveal a potential target for new treatments. 

Other helpful things to know about epigenetics: 

• Epigenetic modifications are heritable and can be passed between generations.
  
• Epigenetic changes may be reversible (unlike genetic changes). 
  
• Your epigenetics change throughout your life. 
  
• Epigenetics explains how early experiences can have lifelong impacts.
  
• Young brains are particularly sensitive to epigenetic changes.
  
• Epigenetics explains how people with identical DNA can have dramatically different looks and behaviors (phenotypic differences).
  

Epigenome: A collection of chemical marks that accumulate on a gene’s DNA as the body develops (also known as epigenetic marks or epigenetic signatures). Known as the epigenome, this collection of marks “tells” the gene what to do, where to do it, and when to do it.

Equal-access health system: A description of health care systems that aim to provide every person—regardless of their social, economic, or demographic status—with the care and resources they need to be healthy. Equal-access health systems help address barriers to care. For instance, they may provide transportation and increase access by creating more community health centers. They also set a foundation for ongoing equity and equality in health care by providing health education to all communities, increasing diversity in the health care workforce, and collecting data on race and ethnicity as well as other factors. 

Etiology: The study of the causes of a disease. There are many possible causes of cancer. Research is showing that both genetics (genes passed on from your parents) and lifestyle (including exposures to carcinogens) are major factors involved in the development of many cancers. See also carcinogen, gene.

Experimental study: When researchers introduce an intervention and study the effects. Randomized controlled trials are a type of experimental study. Unlike correlational research where a scientist looks for associations among naturally occurring variables, in experimental studies, the researcher may introduce a change and then monitor its effects. 

Federal Poverty Line (FPL): The income level that’s used to set eligibility limits for several programs and benefits in the United States. It’s published each year by the US Department of Health and Human Services. These programs include Medicaid, Children’s Health Insurance Program (CHIP), Supplemental Nutrition Assistance Program (SNAP), Supplemental Nutrition Program for Women, Infants, and Children (WIC), and other “welfare” programs.

FPL (see Federal poverty line) 

Functional precision medicine: A pre-clinical research platform where scientists use live tumor cells taken from patients to identify new drugs, including the identification of biomarkers to personalize the use of these drugs.

GxE (gene-environment interaction) (see genome-wide interaction scan and genome-wide association study)

Gene: A piece of DNA. Genes have information on inherited traits such as hair color, eye color, and height, as well as susceptibility to certain diseases. Every person has more than 20,000 genes.

Most genes are the same in all people and they vary in size based on how many DNA bases they include. Less than 1% of genes are slightly different between people.

Some genes carry instructions to make proteins, which are required for the structure, function, and regulation of the body’s tissues and organs.

All the genes in a cell aren’t needed all the time. So the body has ways to turn them “on” (gene expression) and turn them “off.” For instance, actions such as coiling and uncoiling the DNA can turn a gene on or off based on how close it is to other genes. The mechanisms that turn the genes on and off can be influenced by lifestyle, environment, and age.

Gene editing (see CRISPR)

Gene expression: The process of the body turning encoded information in a gene into a function. For instance, a gene may have the code for making a certain protein. When the gene is “expressed,” a protein is made. Proteins dictate a cell’s function. 

The term gene expression communicates how many, how often, and when proteins are created from the instructions within the genes. Some researchers describe gene expression as volume control. Epigenetic changes affect gene expression to turn genes “on” and “off” (compared genetic changes can alter which protein is made, but not how much or when). 

Genetic changes (see genetic mutation)

Genetic marker: A gene or a specific DNA sequence that, like a landmark, is at a known, distinctive location on a chromosome—called the locus. These markers can help associate an inherited disease with the gene that was responsible for the inheritance. Genetic markers and genes that are close to each other on a chromosome tend to be inherited together, so scientists can use markers to better understand location of genes. See SNP.

Genetic mutations (also known as genetic variants and genetic changes): Permanent changes in the DNA sequence of a gene are called gene mutations. Some scientists think that “gene variant” is a more accurate term because changes in DNA do not always lead to disease. Sometimes the terms are used as synonyms.

Genetic predisposition or genetic susceptibility: People who inherit certain changed genes that make them more likely (more disposed or more susceptible) to develop cancer are said to have a genetic predisposition to a cancer or certain types of cancer. Sometimes this is referred to as having a family cancer syndrome. But having a genetic predisposition doesn’t mean that person will develop cancer. And if they do develop cancer, it may not be caused by the inherited genetic mutation.

Genetic susceptibility (see genetic predisposition)

Genetic variants (see genetic mutations)

Genome: A complete set of DNA. Almost all of our cells contain two copies of a person’s genome.

Genome editing (see CRISPR)

Genome-wide association study (GWAS): A study that rapidly scans a person’s complete set of DNA (called the genome) to look for small genetic variations that are associated with a particular disease (or another trait). Each small variation is called a single nucleotide polymorphism (SNP). Each study can look at 100s or 1,000s of SNPs at the same time.

The GWAS lays the groundwork for personalized medicine. The identification of  genetic associations, and how many times they occur in the genome of people with a disease can help scientists pinpoint genes that are likely involved in the disease’s development. With that information, they may be able to develop more individually-tailored strategies to prevent, detect, and treat the disease. This type of study is useful in finding genetic variations that contribute to complex diseases like cancer, as well as asthma, depression, diabetes, heart disease, and psychiatric illnesses.

Genome-wide Interaction Scan (GWIS): One method for a genome-wide association study (GWAS) to improve the understanding how genetic variants interact with environmental factors (GxE) or drugs to contribute to development of a disease in certain groups of people.

Genomics: (see human genomics)

Germline pathogenic variations: A type of mutated gene that gets passed down from a parent to child and that causes disease, such as cancer. The BRCA1 and BRCA2 mutations are examples because they are passed down by parents and increase the risk of developing several types of cancer.

Germline variations: The type of mutated gene that are passed from a parent to a child. Germline variations that cause disease are germline pathogenic variations.

Global cancer burden: An assessment of the number of cancer cases and the effects of cancer across the world. The global cancer burden may be lowered by improving cancer prevention programs, broadening cancer screening programs, expanding high-quality treatment and patient support, and prioritizing public health awareness and education campaigns in every country. See ACS Global Cancer Control Work.

Gut microbiome: A collection of microorganisms like bacteria, viruses, and fungi that mostly live in the digestive tract. Every person's gut microbiome is uniquely shaped by their diet, lifestyle, genetics, and environment. Gut bacteria help with day-to-day functions like synthesizing vitamins, digesting food, and metabolizing drugs. They also help regulate the immune system and protect the body from potentially harmful bacteria. Recent findings have shown that the gut microbiome can help cancer grow and also help keep it from growing.

GWA: (see genome-wide association study)

GWIS: (see genome-wide interaction scan)

Health care barriers: Factors that prevent a person from getting to (accessing) quality health care and services. Examples of health care barriers include lack of adequate health insurance, distant location of health centers, lack of transportation, and no, or limited, paid or unpaid time off from work.

Health disparity: Health disparities are usually noticeable and significant differences between population groups in regard to their health, health care, or both, in ways that are not fair or equal. Cancer disparities are one type of health disparity. Health disparities contribute to health inequalities. 

Notable differences/disparities can be in the number of people receiving care, access to nearby care, sufficient health insurance, quality of care, and more.

Such differences are preventable, as they're closely linked with economic, political, social, and/or environmental disadvantages. Health disparities may occur because of:

• Age
• Discrimination or exclusion, or both
• Disability
• Education
• Gender (or gender identity)
• Geographic location
• Income
• Literacy
• Mental health
• National origin
• Race or ethnicity
• Religion
• Sexual orientation or gender identity
• Socioeconomic status

Health equality: Providing everyone with the same tools and resources for health care. Compare with health equity.

Health equity: The state in which everyone is able to reach their full health potential, and no one is at a disadvantage for attaining this potential on the basis of race/ethnicity, gender, health insurance coverage, disability, place of residence, or other social circumstances, such as lack of access to good jobs with fair pay, quality education and housing, safe environments, and health care.

Equity is the fair treatment, access, opportunity, and advancement for everyone while addressing needs and eliminating barriers that prevent the full participation and success of all people.

Achieving health equity requires removing obstacles to health such as poverty and discrimination, as well as their consequences, including powerlessness and lack of access to good jobs with fair pay, quality education and housing, safe environments, and health care.

Health equity is not the same as health equality. Equity acknowledges that people have different circumstances or barriers they need to overcome, often through no fault of their own. These barriers are often because of deeply rooted, longstanding inequities at all levels of society that will take an intentional effort to address in order to have equal cancer outcomes. Because of this, the tools and resources needed for health care need to be different from one person to the next.

High-thoughput sequencing (see next-generation sequencing)

Hispanic: A broad term that refers to people descended from Spanish-speaking countries or with Latin American (South America, Mexico, Central America, and certain Caribbean islands, including Cuba, Jamaica, and others.) ancestry. The term Hispanic is more commonly used in the Eastern US and is generally preferred by those of Caribbean and South American ancestry or origin. Hispanic is considered an ethnicity, as Hispanic people can be of any race. See Latino.

Human genomics: The study of a person’s genome—a complete set of DNA, including all of its genes.

Incidence (See cancer incidence)

Interleukins: Proteins required for controlling acute inflammatory responses in the body. Interleukins are the body’s defense against “invaders,” like wounds, viruses, or diseases. 

Interleukin-6 (IL-6): A protein produced by various cells in the body to help regulate immune responses. The production of c-reactive protein (CRP) is thought to be linked with the production of IL-6. Testing the levels of interleukin-6 is a potentially useful mark of how well the immune system is functioning. Too much IL-6 has been linked with diabetes, rheumatoid arthritis, and cancer. Both physical and psychological stress can cause temporary increases in IL-6.

Internet of Everything (IoE): A 21st century digital system is an intelligent network of people, process, data, and things (objects, devices, appliances, and so forth that use implanted sensors to communicate across the network). This interconnectedness allows data from all devices to be analyzed and processed together. IoE works in sync with technologies such as artificial intelligence, machine learning, and the cloud. These processes ensure the correct information is relayed to the right destination across the network and to leverage data faster.

Internet of Things (IoT): A subset of the Internet of Everything, which includes those devices with sensors or other technology that are connected by a network and that can exchange data over the internet without human intervention. Examples of IoT devices include pacemakers, smart thermostats, home security systems, and self-driving cars.

Intervention: A program or set of activities designed to help people or populations change a particular behavior (like sitting too much or forgetting to put on sunscreen) that increases their risk for a particular disease.

In vitro: A Latin term that means grown and studied in a dish, or in the lab, compared to being grown in a living being—in vivo.

In vivo: A Latin term that means grown and studied in a living being, such as a lab mouse or human

Latino: A broad term that refers to people in the US with Latin American ancestry. Unlike Hispanic, Latino includes people from Brazil, who speak Portuguese. Latino has replaced the terms Chicano and Mexican American and is used primarily west of the Mississippi River. Like the word Hispanic, the word Latino identifies an ethnicity, as Latino people can be of any race. Latino is used for males, Latina for females, and Latinx to be gender neutral. See also Hispanic.

Loci (see locus)

Locus (plural loci): A term that identifies the physical location of a specific gene on a chromosome. The locus of a gene is sometimes compared to a neighborhood and the region of the chromosome as the city.

Longitudinal study: A research design that involves repeated observations or measurements of the same variables—such as weight, existence of a disease, like cancer, and foods eaten (diet)—over a short or long period of time—sometimes lasting decades. Researchers don't interfere with the participants' day-to-day activities but only collect qualitative and quantitative responses through surveys, interviews, or other tools. Longitudinal studies are a method of correlational research, meaning it helps scientists discover the relationship between variables in a specific population.

Machine learning: Machine learning is a subfield of artificial intelligence. It’s a technology that uses current and historical data along with algorithms and statistics formulas to train computers to recognize patterns to perform tasks without having a specific set of instructions (like software or code) to follow. It can analyze and make decisions about large amounts of complex data exponentially faster than people can, and it can improve with experience. Machine learning is used for such things as fraud detection and recommending products based on previously bought items. See deep learning.

Marker (see biomarker)

Medicaid expansion: The part of the Affordable Care Act that called for increasing the number of low-income people in the United States who qualify for the health insurance coverage provided by Medicaid, a government program run by each state.

Metabolites: Small molecules that are made and stored when the body breaks down food, drugs, or its own tissue and that are affected by the environment and diseases like cancer.

Metabolomics: The study of small molecules (called metabolites) that are made and stored when the body breaks down food, drugs, or its own tissue. Metabolites are affected by the environment and diseases like cancer.

Microenvironment (see tumor microenvironment)

Mitochondria: Structures in normal and tumor cells that generate most of the energy needed to power the cells’ (or tumors’) biochemical reactions required to function and grow. Mitochondria act like a digestive system that takes in nutrients, breaks them down, and creates energy for the cell.

Molecular marker (see biomarker)

Monitoring biomarkers: Biomarkers that help recognize the status of disease or side effects of treatment. Tumor DNA (ctDNA) is a monitoring biomarker for certain metastatic cancers.

Mutation (see genetic mutation)

Native Hawaiian and Other Pacific Islander (NHPI): A broad term that refers to a person having origins in Hawaii (Hawaiʻi), Guam (Guåhan), Samoa (Sāmoa), Fiji or other Pacific Islands throughout Polynesia, Micronesia, and Melanesia.

Natural killer cells (NK cells): These immune cells typically patrol the bloodstream, seeking out cells infected with viruses and tumor cells that they destroy in their early stages before viruses or cancer cells spread. They’re called “natural” killers because they can recognize potentially harmful cells and kill them without ever having seen them before.

NK cells work by scanning cells for markers that indicate whether the cells are healthy or diseased. When they detect harmful cells, NK cells release deadly chemicals and kill them.

NK cells are highly efficient at killing tumor cells within the circulating blood and can help block metastasis, but they are less efficient at killing tumor cells in the microenvironment.

Another class of NK cells communicate rather than kill. They release cytokines, which “alert” other immune cells to attack harmful cells. 

Next-generation sequencing (also known as NGS and High-throughput sequencing): Technology that allows for simultaneous sequencing of DNA and RNA in multiple people at the same time. Compared to traditional sequencing, which determines the sequence one section at a time, next-generation sequencing in much faster, less expensive, and delivers a much larger magnitude of information. Making sense of these huge datasets requires bioinformatics and computational biology. NGS has revolutionized the field of personalized medicine (precision medicine).

NGS (see next-generation sequencing)

Observational study: When researchers observe the effect of a risk factor, diagnostic test, treatment, or other intervention without trying to change who is or isn't exposed to it.

Oncogenes: A group of genetic mutations that have the potential to cause cancer and that give cancer cells an advantage to grow and survive.

Oncogene addiction: The dependency of certain tumor cells on a specific, individual oncogene to grow and survive.

Oncogenesis (see carcinogenesis)

Oncogenic fusion gene: A hybrid gene formed from 2 or more previously independent genes that plays a leading role in the development and progression of cancer. These hybrid, fused genes are read (transcribed) and translated as a single unit, which may lead to the production of defective proteins that cause cancer to grow and spread.

The prevalence of fusion genes varies widely across different cancers, and many fusion genes are specific to certain cancer sub-types. Rapidly and accurately identifying fusion genes can be an important part of diagnosis because specific gene fusions characterize cancer subtypes. A stratified diagnosis can predict a patient's prognosis, response to treatment, and survival.

Fusion genes are potentially excellent sites for new treatments to target. Several drugs have been successfully developed to inhibit fusion genes.

Pathogenic mutations (see pathogenic variants)

Pathogenic variants (PVs, also known as pathogenic mutations): Genetic variants or mutations that lead to disease.

Pharmacokinetics: The study of how the body interacts with medicines from the time a person takes a drug throughout its journey in the body. 

Ploidy: The number of sets of chromosomes contained in a cell, whether it’s a normal cell or cancer cell. See also aneuploid, diploid.

Poverty level (see federal poverty line and 138% of federal poverty line)

Precision medicine (also called personalized medicine): A clinical approach for medical prevention and treatment that's tailored based on a person's lifestyle, environment, and the specific genes, proteins, and other substances in their body. Precision medicine is the opposite of the one-size-fits-all approach to prevention and treatment, where an average strategy applied to everyone. A personalized approach  helps doctors and researchers more accurately predict which prevention and treatment methods will work for a specific disease in a particular person.

The 2 types of treatment most often used in precision medicine are:

• Targeted therapy, which uses medicines designed to attack a specific target on cancer cells
• Immunotherapy, which uses medicines that help the body’s immune system attack the cancer

Preclinical studies: Research that takes place before any testing in humans is done—before clinical trials. Preclinical studies may study if a drug, procedure, or treatment is likely to be useful. In the commonly used description about the research continuum, “bench to bedside,” preclinical studies are the bench—meaning they occur in a lab setting. Preclinical studies may be conducted in a test tube or cell culture (in vitro) or in animals, such as mice (in vivo).

Predictive biomarkers: Biomarkers that signal the likelihood a person has to develop a reaction after exposure to a disease, treatment, or substance in the environment. For instance, presence of the hormone ER (ER+) in a breast tumor is a predictive biomarker that tamoxifen may be an effective treatment.

Predisposition genes (see cancer-predisposition genes and genetic predisposition)

Prevalence (see cancer prevalence)

Prognostic biomarkers: Biomarkers that indicate the chances of a disease progressing or recurring. For instance, the protein HER2 is a prognostic biomarker for breast cancer.

Promoter (also known as DNA promotor): A region of DNA where transcription (copying the information in DNA to mRNA) of a gene is initiated. Promotor regions describe the direction of transcription and point out which DNA strand will be transcribed.

Promoters work with DNA regions known as enhancers to ensure a good copy of that gene. DNA bends to put the enhancer section close to the promotor section. Mutations can occur in the coding (enhancer region) or in the promotor region. Many studies suggest that DNA promotors may be the main cause of many human diseases, especially diabetes.

Prospective Cohort Study: A long, on-going (longitudinal) research study that captures and compares years of data from a group of people (cohort) to learn how specific characteristics or risk factors affect the rate of developing diseases such as cancer.  Prospective means data is collected before anyone has developed cancer. Cohort studies are a type of observational study.

Redlining: Redlining refers to the time from the 1930s to the 1960s when it was legal for banks and other financial lenders in the United States to refuse applications based on the neighborhood where the applicant lived. Specifically, lenders refused mortgages to buy a house or to refinance home improvements from creditworthy Black people and others who lived in poor neighborhoods.

This deliberately discriminatory practice reinforced racial and socioeconomic segregation and kept families in those neighborhoods from building wealth through equity and moving away to middle- or upper-class neighborhoods. Redlining also cut off specific neighborhoods from investments in health care, education, and other services like public transportation and green spaces.

The effects of redlining have continued—for decades. Homes in formerly redlined districts are chronically undervalued. People who live in formerly redlined areas have a higher chance of:

• Exposure to environmental hazards, such as air pollution and extreme heat, which increases the prevalence of chronic stress and infectious diseases.
• Developing health issues, including cancer. 
• Having limited access to cancer care, which often leads to delays in diagnosis and treatment—and that can result in worse outcomes.

Relative cancer survival rate: A way to determine whether a type of cancer shortens the expected lifespan. Relative survival rates compare the survival of a group of people with cancer to the survival of a group of people in the general population without cancer of the same age, race, and sex for a stated period of time (usually 5 years). 

For example, if the 5-year relative survival rate for a specific type of cancer is 90%, it means that people with that cancer are 90% as likely to be alive 5 years after their diagnosis compared to people of the same age, race, and sex without cancer.

Research continuum: The full scope of research—often referred to as bench to bedside. Research may start in a research lab (pre-clinical research or research at the bench), occur as part of clinical trials, be done by health care providers or within health care systems (at the bedside), and be conducted within communities.

Response biomarkers: Biomarkers that help confirm whether a prevention method or treatment worked. For instance, after vaccination, antibodies are the response biomarkers.

Ribonucleic acid: See RNA.

RNA (ribonucleic acid): RNA is found in all living cells of the body. Its most notable role is to act as a messenger (mRNA) by contains instructions from DNA that are translated by the cell to make proteins. When RNA does not carry a code for a protein, it’s called non-coding RNA (ncRNA). There are many additional types of RNA with various functions within the cell.

RNA, like DNA, is made of nucleotides (chains of nucleic acids). See also DNA.

RNAseq: See RNA sequencing.

RNA sequencing (RNAseq): A technique used to learn the exact order of the nucleotides that make up RNA molecules in healthy or diseased tissue or cell. It provides a picture of how the blueprint (DNA) is being read.

RNAseq is a powerful tool for understanding cancer at the molecular level (how individual cells employ their mRNA and proteins) and for developing new strategies to prevent or treat cancer. For instance, RNAseq allows scientists to compare how genetic instructions change before and after drug treatment.

RNAseq can reveal gene fusions, splicing variants, mutations, and differences in gene expression between cell samples.

Scientists can use RNA sequencing for analysis of:

• Cell collections
• Tissue sections, called bulk RNA sequencing
• Liquid biopsies (See Biopsy Types and Liquid Biopsy: Past, Present, Future.)
• Single cells, called single-cell RNA sequencing or scRNA-seq, which can distinguish single-cell RNA biology up to 20,000 individual cells simultaneously, and show how cells change over time.

Single nucleus RNA (snRNA seq): A technique to isolate RNA from the nucleus of a cell.

Single-cell resolution/Single-cell analysis (scRNA-seq, also known as single-cell imaging): The use of new methods and technologies that show more details than a microscope, allowing researchers to see a different view of single cells in tissue. This technique reveals the specific population of cells in a selected area of tissue. With these tools, scientists can analyze each cell individually and learn how the position of each cell has a role in the tissue’s architecture. This detailed information is critical to better understanding the biological function of both normal and diseased tissues.

Spatial RNA sequencing, spRNAseq, also called spatial transcriptomics): This method allows scientists to view a specific region within a cell, then sequence all RNA transcripts (copy of DNA instructions) found in that region. Using this, scientists can map the variation of gene expression (which proteins are made by the cells) across the region of interest.

Organisms function based on the spatial organization and spatial of cells. If spatial orientation is disrupted, there could be a loss of biological function.

A better understanding of spatial information will help scientists better understand how tumor cells communicate with each other, escape tracking by the immune system, become resistant to drugs, and metastasize.

For spatial sequencing, scientists use immunofluorescence microscopy and next-generation sequencing to determine the transcripts in the region. 

Safety biomarkers: Biomarkers that help identify possible toxic responses to treatment or harmful environmental exposures. For instance, creatinine is a safety biomarker for drugs that can potentially affect the kidney.

Screening prevalence: The number of people in a population who receive cancer screening.

Sedentary: Sitting, reclining, or lying down while awake and expending very little energy. 

Signature marker (see biomarker)

SNP (single nucleotide polymorphism): Pronounced “snip,” this is the most common type of genetic variation in people. A SNP is a DNA variation that involves one DNA “building block,” called a nucleotide, replacing another one. 

Scientists use the location and number of these simple swaps to help predict how a person will respond to certain drugs or toxins and a person’s risk of developing a certain disease, such as cancer, diabetes, and heart disease. SNPs are genetic markers that help scientists locate the genes that are associated with a specific disease. 

Snus: Rhyming with "loose," this smokeless tobacco product originated in Sweden and is a small pouch placed between the upper lip and gum. The pouch contains powdered tobacco, water, salt, and sometimes flavor. The liquids produced are swallowed rather than spit out like they are with snuff products. Finished pouches may be thrown away. 

Snus contains nicotine, which is addictive. Nicotine is absorbed into the bloodstream through the soft, moist lining of the gums, tongue, and inside of the cheeks and lips (the oral mucosa). Snus poses health risks because it contains tobacco-related toxicants that may lead to an increased risk of developing diseases such as oral cancer and gum disease.

Federal and state laws in the United States prohibit the sale of snus to people younger than 18.

Social determinants of health: A mix of conditions of daily life in which people live, work, learn, play, worship, and age influenced by a broad set of forces and systems that shape those conditions, including social norms, social policies, political systems, and economic policies and climate and systems.

Social determinants of health can positively or negatively affect the occurrence of cancer because of their effects on educational and job opportunities, income, insurance coverage, housing, transportation, public safety, food security, social inclusion and non-discrimination, and access to affordable health services of high quality.

Structural racism and discrimination are examples of long-lived social determinants of health that result in social inequities and discriminatory policies.

Stroma: The cells and tissues that support and give structure to organs, glands, or other tissues in the body. It’s made mostly of connective tissue (made mostly of fibroblasts), blood vessels (lined by endothelial cells), lymphatic vessels, immune cells, and nerves.

The stroma provides nutrients to other tissues and organs, removes waste and extra fluid, and may be involved in the body's immune response, modulating inflammation levels. When stromal cells secrete growth factors, they promote tumor growth, invasion, and metastasis.

Structural racism/Systemic racism: Normalized historical, cultural, political, and institutional practices that govern society and benefit White people and disadvantage people of color. These can include housing policies, educational systems, and employment practices that reinforce and perpetuate inequities among racial groups.

Survival rate (see relative cancer survival rate)

Survivorship: The time in a person's life from the diagnosis of cancer until death. The study of survivorship evaluates a person's quality of life, physically, mentally, and spiritually.

Susceptibility biomarker: A biomarker that signals the potential, or risk, a person has to develop a disease before they have symptoms. For instance, low-density lipoprotein (LDL) cholesterol is a susceptibility biomarker for heart disease.

Targeted therapy: A type of cancer treatment that uses drugs or other substances designed to “target” a specific aspect of cancer cells, like a mutated gene, and kill them without harming normal cells. Targets may also be in the tumor’s microenvironment, such as a protein that sends messages to tell the cancer cell to grow and copy itself.

Different targeted therapies work differently. For example, a targeted therapy can block or turn off signals that make cancer cells grow, or it can signal the cancer cells to destroy themselves.

Targeted therapy is an important type of cancer treatment, and researchers will develop more targeted drugs as they learn more about specific changes in cancer cells. 

tbNGS (see next-generation sequencing)

TNBC (see triple-negative breast cancer)

Tobacco-related toxicants: Chemicals found in tobacco products and smoke. These chemicals highlight the dangers of using tobacco products because they are linked with health problems that include cancer, heart disease, and respiratory illnesses. 

Triple-negative breast cancer (TNBC): A subtype of breast cancer that grows faster and is more likely to spread and recur. It is more common in women younger than age 40, who are Black, or who have a BRCA1 genetic mutation. 

It’s called triple negative because the cancer cells in TNBC don’t have receptors for the hormones estrogen (ER) or progesterone (PR). Plus, TNBC cells make very little or none of the protein called HER2 (human epidermal growth factor). That means all 3 biopsy tests to check for these hormones and the HER2 protein have "negative" results.

Tumor-based next-generation-sequencing (see next-generation sequencing)

Tumor microenvironment: If a tumor is a castle, the tumor’s microenvironment is everything immediately around the castle—like the moat, high walls, courtyard, and soldiers—that affects how easy it is to get to the castle. The immediate area surrounding a tumor includes blood vessels that provide nutrients to the tumor, immune cells that may protect the tumor, structural matter called the extracellular matrix, and other cells that support the tumor (like stromal cells) or that make space for it to get larger.

A tumor and its microenvironment constantly interact, which influences if and how the tumor grows. Cells in the microenvironment can perform both pro- and anti-tumor functions, controlling how the cancer progresses and spreads.

This relationship between the microenvironment and tumor means successful cancer treatments often need to target more than just the cancer cells. They may need to target cells in the microenvironment to cut off the tumor’s nutrients or weaken its protection. 

Tumorigenesis (see carcinogenesis)

Underrepresented minorities (URM) in health-related science: Racial and ethnic groups that are particularly underrepresented across many career stages: African American/Black, Hispanic/Latino, American Indian and Alaska Native, Native Hawaiian and other Pacific Islander groups. The ACS Diversity in Cancer Research (DICR) program focuses on racial and ethnic underrepresented minorities.

Wnt gene (see Wnt signaling pathway)

Wnt protein (see Wnt signaling pathway)

Wnt signaling pathway: A complex and diverse communication channel in cells that has many signaling branches. Wnt genes code for a large family of Wnt proteins that “carry messages” across the Wnt pathway. These messages regulate many critical cell functions, including the beginning and end of cells.

In the tumor microenvironment, Wnt signaling can turn immune cells “on and off,” regulating the cell’s anticancer immune response, meaning the signals can help tumors grow or stop them from growing.

Defective, or disrupted, Wnt signaling is part of the cause of cancers in the breast (including triple-negative breast cancer), cervix, colon, lung, and skin, as well as some blood cancers. Multiple players along the pathway have been identified as targets for anticancer drugs to disrupt signals that let cancer cells grow.