Understanding Cancer Research Terms

Get more out of American Cancer Society studies on epidemiology, statistics, genetics, and other complex topics with this glossary of terms used in cancer research, explained in plain language for nonscientists. 

Abstinence: The practice of choosing not to do a certain behavior or give into a desire or addiction, such as using tobacco or alcohol.

Advanced cancer: A general term describing the late stages of cancer, when the disease has spread from where it started (the primary site) to other parts of the body. When the cancer has spread only to the nearby areas, it is called locally advanced cancer. If it has spread to distant parts of the body, it is called metastatic cancer. See also metastasis, metastasize.

African American/Black: People in the United States who can trace their lineage to Africa. Some Black people do not identify as African American. The Black lineage contains many histories, cultures, and experiences, including Afro-Caribbean and Afro-Latino populations.

Age-adjusted cancer death rates: A cancer death rate that has been adjusted with a math calculation to allow for differences in age so that 2 populations can be more directly compared. 

American Indian and Alaska Native (AIAN): A person with origins in any of the First Peoples in North, Central, and South America who maintains tribal affiliation or community attachment. These include Navajo, Blackfeet, Inupiat, Yup’ik, and Central and South American Indian groups. The AIAN is a federally recognized tribal entity with certain rights of self-government and are entitled to receive US federal benefits, services, and protections.

Apoptosis: Programmed cell death. Apoptosis is controlled by genes that cause cells to die at certain times, for example, when DNA is damaged. This type of cell death is different from the process of cell death by decay. Some drugs used to treat cancer cause apoptosis.

Behavioral research: Research into what motivates people to act the way they do. The results of such research can be used to help encourage people to adopt healthy lifestyles and follow life-saving screening and treatment guidelines.

Biomarker (also called molecular marker or signature molecule): A measurable molecular, genetic, chemical, or physical characteristic in the blood or other bodily fluids, such as sweat and tears, that is a sign of normal or abnormal process or of a health condition or disease. A biomarker may be used to see how well the body responds to a treatment for a disease or a condition. The US Food and Drug Administration (FDA) classifies 7 categories of biomarkers: susceptibility biomarkers, diagnostic biomarkers, response biomarkers, safety biomarkers, prognostic biomarkers, monitoring biomarkers, monitoring biomarkers, and predictive biomarkers.

Biorepository: A facility that collects, catalogs, and stores samples of biological materials. The ACS Cancer Prevention Studies biorepository includes blood, urine, buccal cells (from the inside of the cheek), cancer tissue, and stool.

Biospecimen: A sample of a biological material, such as blood, urine, tissue, cells, or stool collected from participants for research.

BRCA1: A gene which, when damaged (mutated), puts a person at higher risk of developing breast, ovarian, prostate, and other types of cancer, compared to people who do not have the mutation. See also gene, mutation.

BRCA2: A gene which, when damaged (mutated), puts a person at higher risk of developing breast, ovarian, prostate, and other types of cancer, compared to people who do not have the mutation. See also gene, mutation.

Cancer burden: How the number of cancer cases and results of cancer affect a country, community, family, or one person. For example, the cancer burden for a specific person depends on their risk factors for cancer, how well they manage their modifiable risk factors, how closely they follow the recommended cancer screening schedule, if they develop cancer, and their access to high-quality cancer treatment. See What Is Cancer Control?

Cancer care continuum: The full scope and progression of cancer care, from promoting good health (wellness) to preventing cancer, detecting it early, diagnosing it, treating it, and surviving it.

Cancer control: Organized programs that focus on reducing the number of people who develop cancer, have complications from it, and die from it. It uses approaches that have been tested through research to control the number of cancer cases as well as the effects of cancer. Programs may include cancer prevention and early detection, treatment, palliative care, patient and family services, professional education and training, and cancer survivorship care. A cancer control program is successful when it assures that people are as healthy as possible, regardless of race, age, gender, location, social level, or economic status. See What Is Cancer Control?

Cancer death (see cancer mortality)

Cancer death rate (see cancer mortality rate)

Cancer disparities: Harmful differences between population groups, such as differences in the number of people who receive standard cancer care or in how well they do (their outcomes) after receiving care. For instance, without standard cancer care, people are more likely not be diagnosed with cancer until it's at a late stage, and they're more likely to die from the cancer. See Cancer Disparities ACS Research Highlights.

Cancer epidemiology research: Studying the distribution and determinants of cancer—who gets it, where they live, and the risk factors that contribute to its development.

Cancer incidence (also called cancer occurrence): The number of new diagnoses of cancer, or new cases, in a group. Incidence counts can give information about a specific group but can’t be used to compare groups because the numbers alone don’t account for the size of the group or age ranges of the people in it. Comparing groups requires cancer incidence rates. Compare to prevalence.

Cancer incidence rate: The number of people who have a new diagnosis of cancer within a defined population (such as people aged 65 and older) and during a specified period of time (like 2019-2021). Incidence rates are usually given as the count per 100,000 population and are adjusted to account for differences in age.

Cancer mortality (also called cancer deaths): The number of people who die from cancer. Death counts can give information about a single group but can’t be used to compare groups because the counts don’t account for the size of the group or age ranges of the people in it. Comparing groups requires cancer death rates. See Understanding Cancer Death Rates.

Cancer mortality rate (also called cancer death rate): The number of people who die from cancer within a defined population such as Black women (but not limited to Black women with cancer) during a specific time period. The cancer death rate is not confined to people with cancer, it includes all people in the population. Cancer death rates are given as the number of deaths per 100,000 of the population. Researchers account (adjust) for age when they calculate death rates so they can track trends over time, and so they can compare groups. Cancer death rates are the best measures researchers use to track progress against cancer. See Understanding Cancer Death Rates.

Cancer occurrence (see cancer incidence)

Cancer-predisposition genes: Genes that are vulnerable to cancer-causing variants or changes (mutations). In some cases, a cancer-predisposition gene is inherited, or passed along from generation to generation. Several dozen cancer-predisposition genes have been identified, and about 5 to 10% of all cancers result directly from those that are inherited from a parent. For example, BRCA1 and BRCA2 are inherited cancer predisposition genes, and mutations on them increase the risk for developing certain cancers.

Cancer prevalence: The number of people in a population with a history of a cancer diagnosis.

Cancer-related outcomes: The results of a cancer diagnosis—how it affects health, quality of life, and length of survival. These outcomes are influenced by a patient’s overall health, access to quality health care, cancer type and stage, response to provided treatments, complications, and follow-up care.

Cancer relative 5-year survival rate: An estimate of the percentage of people who will be alive 5 years after a diagnosis of cancer compared with people who haven’t been diagnosed with cancer. The relative survival rate shows whether a disease shortens life and is used as a way to approximate the expected lifetime. For example, a relative 5-year cancer survival rate of 80% means that compared to the number of people without cancer who are alive, 80% of people with cancer will be living 5 years after their diagnosis.

Cancer surveillance research: Ongoing and systematic collection, analysis, interpretation, and reporting of cancer data about the new cancer cases, extent of disease, screening tests, treatment, survival, and death. Its goal is to use data to guide public health policy and action, such as the distribution of health care resources.

Cancer survival rate: The percentage of people who survive a certain type of cancer for a specific amount of time (often 5 years). For example, if a 5-year survival rate is 77%, it means that of all the people who have that type of cancer, 77 out of every 100 will be living at least 5 years after their diagnosis.

Cancer survivor: The American Cancer Society describes anyone who has been diagnosed with cancer as a cancer survivor, regardless of whether they are actively receiving treatment. 

Cancer treatment outcomes: How well a person is doing after being treated for cancer, which can depend on how well they respond to treatment, the treatment's side effects, their other health issues, and follow-up care, as well as on the facility where they received care and its geographic location.

Cohort: A group of people, including groups of people who are in a study. See prospective cohort study.

Complete response: When tests after treatment show no signs of disease. A period when a disease is under control. A complete response may not be a cure.

Correlation/Correlational research: The process of establishing a relationship or connection between 2 or more measures.

Correlational research design investigates the relationship between 2 or more variables without interfering with or manipulating them. Results of a correlational study may find a positive or negative relationship, a linear or non-linear relationship, or a partial or multiple relationship. An example of a positive correlation is height and weight—taller people tend to be heavier, and vice versa. In some cases, positive correlation exists because one variable influences the other—such as ice cream sales and temperature. In other cases, the 2 variables are independent from one another and are influenced by a 3rd variable which may or may not be identified. Scientists can calculate the strength of a relationship between variables, but they cannot assume cause and effect.

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

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.

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

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. 

Functional precision medicine: 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.

Genetic mutations (also known as genetic variants): 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)

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.

Health care barriers: Factors that prevent a person from getting to (accessing) quality health care and services, which may include lack of adequate health insurance, location of health centers, available transportation, and time off from work.

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.

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.

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 also Latino.

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

Incidence (See cancer incidence)

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.

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.

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.

Metabolomics: The study of small molecules, called metabolites, 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.

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.

Native Hawaiian and other Pacific Islander (NHPI) groups: This umbrella term includes people with origins in any of the original peoples of Hawaii, Guam, Samoa, or other Pacific Islands.

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.

Pathogenic mutations (see pathogenic variants)

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

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

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. Presence of the hormone ER (ER+) in a breast tumor is a predictive biomarker that tamoxifen may be an effective treatment.

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

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.

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. After vaccination, antibodies are the response biomarkers.

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

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

Social determinants of health: Non-medical factors that influence health. These include conditions in the environments where people are born, live, work, play, worship, and age that affect a wide range of health, functioning, quality-of-life outcomes and risks, and the social, economic, and political systems that shape the conditions of daily life.

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.

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. Low-density lipoprotein (LDL) cholesterol is a susceptibility biomarker for heart disease.

Under-represented minorities (URM) in health-related science: Racial and ethnic groups that are particularly under-represented 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 focus on racial and ethnic under-represented minorities.