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At our National Cancer Information Center trained Cancer Information Specialists can answer questions 24 hours a day, every day of the year to empower you with accurate, up-to-date information to help you make educated health decisions. We connect patients, caregivers, and family members with valuable services and resources.
Or ask us how you can get involved and support the fight against cancer. Some of the topics we can assist with include:
For medical questions, we encourage you to review our information with your doctor.
Cancer occurs as a result of changes (mutations) in the genes inside our cells. Genes, which are made of DNA, control nearly everything our cells do. Some genes control when our cells grow, divide into new cells, and die. Changes in these genes can cause cells to grow out of control, which can sometimes lead to cancer.
A risk factor is anything that increases your chances of getting a disease such as cancer. Different cancers have different risk factors. In many cases, it’s not clear what causes the gene changes that lead to cancer.
Some people inherit gene mutations from a parent that increase their risk of certain cancers. In people who inherit such a mutation, this can sometimes lead to cancer earlier in life than would normally be expected. Examples include:
Still, most cancers in young adults are not caused by inherited gene changes.
In older adults, the gene changes that lead to cancer are often acquired over a person’s lifetime. Some of these changes occur for no obvious reason. But many cancers are linked to lifestyle-related risk factors such as smoking, being overweight, eating an unhealthy diet, not getting enough exercise, and drinking too much alcohol. Exposures to things in the environment, such as radon, air pollution, chemicals in the workplace, or radiation during medical tests or procedures, also play a role in some adult cancers.
These types of risk factors usually take many years to influence cancer risk, so they are not thought to play a large role in cancers in children, teens, or young adults.
Still, there are some known causes of cancer in young adults. For instance:
Still, these and other known risk factors probably account for only a small portion of cancers in young adults overall. Many gene changes that lead to cancer in young adults are likely to just be random events that sometimes happen inside a cell, without having an outside cause.
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.
American Cancer Society. Cancer Facts & Figures 2020. Atlanta, Ga: American Cancer Society; 2020.
Bleyer A. Young adult oncology: The patients and their survival challenges. CA Cancer J Clin. 2007;57:242-255.
National Comprehensive Cancer Network (NCCN). Practice Guidelines in Oncology: Adolescent and Young Adult (AYA) Oncology. Version 1.2020. Accessed at: www.nccn.org/professionals/physician_gls/pdf/aya.pdf on October 2, 2019.
Rock CL, Thomson C, Gansler T, et al. American Cancer Society guideline for diet and physical activity for cancer prevention. CA: A Cancer Journal for Clinicians. 2020;70(4). doi:10.3322/caac.21591. Accessed at https://onlinelibrary.wiley.com/doi/full/10.3322/caac.21591 on June 9, 2020.
Last Revised: June 9, 2020
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