Causes, Risk Factors, and Prevention of Adolescent and Young Adult (AYA) Cancer

The exact cause of many AYA cancers is not known.

Researchers are learning how gene changes play a role, but in most cases, we don’t know what causes these changes.

There are some known risk factors that can affect the risk of developing cancer. Knowing your risk factors might provide opportunities to lower your risk or even prevent cancer in adolescence or young adulthood.

What causes adolescent and young adult (AYA) cancer?

Scientists have found some risk factors for adolescent and young adult cancers, but most people who develop these cancers have no risk factors.

Different cancers have different risk factors.

Researchers have found that gene changes (mutations) play a role in cancer growth and development, but we often don’t know what causes them.

How normal cells become cancer cells

DNA is the chemical in our cells that makes up our genes. DNA controls how our cells function. Changes (mutations) in the DNA inside our cells can sometimes alter the way some genes work. The changes can cause cells to grow out of control and become cancer.

Some genes control when our cells grow, divide into new cells, and die:

• Genes that help cells grow, divide, or stay alive can sometimes lose the ability to turn off. They can become oncogenes.
• Tumor suppressor genes tell cells to stop dividing or cause cells to die at the right time.
• DNA repair genes find and fix damage to the DNA that might happen during cell growth or from the environment.

Acquired versus inherited gene changes in cancer

Cancers can be caused by DNA changes. The changes create oncogenes, turn off tumor suppressor genes, or damage DNA repair genes.

These gene changes can happen before birth. Or they can be inherited from a parent. However, most gene changes that cause adolescent and young adult cancers happen by chance. These acquired or de novo gene changes can result from environmental exposures, such as radiation. But most of them occur by chance.

To learn more, see Gene Changes and Cancer.

What increases the chances of a young person developing cancer?

A risk factor is anything that increases the chances of developing a disease, such as cancer. Different cancers have different risk factors. Most adolescent and young adult cancers are thought to occur because of gene changes that happen by chance.

Some of the most common risk factors for adult cancers take many years to increase cancer risk. These include risk factors like using tobacco, drinking alcohol, having excess body weight, or not being physically active. While healthy habits are important for overall health and may lower lifetime risk of cancer, they likely play a smaller role in most adolescent and young adult cancers.

Exposures to things in the environment, such as radon, air pollution, asbestos, or radiation during medical tests or procedures, also play a role in some adult cancers. These exposures are less likely to play a major role in cancers in adolescents and young adults.

There are two main categories of risk factors for cancer in adolescents and young adults: genetic and environmental.

Genetic risk factors

Genetic risk factors are those that are a part of our DNA. DNA is the substance that makes up our genes and controls how our bodies function. Only a small number of people inherit DNA changes from a parent that increases their risk of cancer. These gene changes are called genetic cancer predisposition syndromes or family cancer syndromes.

These gene changes keep the gene from controlling how cells grow and divide. Some examples include:

• Hereditary Breast and Ovary Cancer (HBOC) Syndrome, caused by a gene change in the BRCA1 or BRCA2 genes, increases the risk of breast, ovarian, and some other cancers.
• Lynch syndrome is caused by changes in genes that can affect how the body repairs damage to the DNA in our cells. It increases the risk of colorectal, ovarian, endometrial, and some other cancers.
• Familial adenomatous polyposis is caused by gene changes in the APC gene. It increases the risk of having colorectal cancer. It can also increase the risk of other cancers, such as medulloblastoma and thyroid cancer, which are more common in adolescents and young adults.
• Li-Fraumeni syndrome is caused by gene changes in the TP53 gene. It increases the risk of certain leukemias, sarcomas, melanoma, breast cancer, and some other cancers.

Find more information in Family Cancer Syndromes.

Most cancers in young adults are not caused by inherited gene changes.

Environmental risk factors

Environmental risk factors are things in our surroundings that increase the risk of getting cancer. These include radiation, chemicals, and certain infections.

Exposure to radiation

It is important to limit your exposure to radiation at any age, but especially at younger ages. There are a few ways young people might be exposed to radiation.

• Exposure to ultraviolet (UV) light from the sun or tanning beds can increase the risk of developing skin cancer. Limiting sun exposure, avoiding tanning beds, and using sun protection can lower this risk.
• Low levels of radiation are used in some imaging tests, such as x-rays and CT scans. Frequent imaging tests can increase the risk of leukemias and lymphomas. Most doctors recommend that children avoid these tests unless they are necessary.
• Radiation treatment given to people who were treated for cancer at a younger age is a risk factor. These people have a higher risk of developing a second cancer after treatment. This risk depends on the type of radiation, dose used, and where the radiation was given. This type of radiation exposure often can’t be avoided when it’s used to treat cancer, but your care team will only use what is needed.
• Accidental exposure to radiation, such as from atomic bombs or nuclear reactor accidents, can increase the risk of certain cancers, including leukemia, lymphoma, and thyroid cancer.

Exposure to chemotherapy and certain other chemicals

Young people treated for cancer with certain chemotherapy medicines have a higher risk of getting a second cancer, such as acute myeloid leukemia (AML), after treatment.

Some studies also suggest that air pollution and chemicals, such as pesticides, benzene, and PFAS, increase the risk of developing cancer. However, this is more common in older adults.

Infections

Certain infections increase the risk of cancers that affect adolescents and young adults. Some examples include:

• Human papillomavirus (HPV) infections can increase the risk of cervical, head and neck, and some other cancers.
• Human immunodeficiency virus (HIV) infection can raise the risk of non-Hodgkin lymphoma, Kaposi sarcoma, and some other cancers.
• Epstein-Barr virus (EBV) infections can increase the risk of certain types of lymphoma and nasopharyngeal cancers.

Can adolescent and young adult (AYA) cancers be prevented?

Limiting exposure to radiation, certain chemicals, and infections may lower the risk of some adolescent and young adult cancers. However, because the cause of all cancers in adolescents and young adults is not known, many cancers cannot be prevented.

If an adolescent or young adult has a known gene change (mutation) or family cancer syndrome that increases their risk of certain cancers, doctors might suggest certain cancer screening tests earlier or more often than most people. Depending on the type of gene change, the care team might suggest ways to prevent or reduce the risk of developing cancer.