People age 18 to 39 who are diagnosed with cancers typically seen in older adults, such as breast and prostate cancer, have a higher-than-expected risk of having a genetic mutation linked to cancer and might therefore benefit from genetic testing, according to a study.
The research is part of the program of the American Association for Cancer Research Virtual Annual Meeting II. Read the abstract of “Germline mutation prevalence in young adults with cancer.”
About early-onset cancer
People diagnosed with early-onset cancer are a distinct group of younger people diagnosed with cancer.
“Some cancers are more typically seen in young adults, such as testicular and brain cancer,” explained Zsofia Stadler, M.D., medical oncologist at Memorial Sloan Kettering Cancer Center, who presented the research. “While cancers typically diagnosed in older adults — such as breast, colon, prostate, and kidney — are very rare in younger people and are what we classify as early-onset cancers.”
Genetic mutations linked to breast cancer
A germline variant is a change, or mutation, in a gene that is inherited from your parents and is in all your DNA.
Three of the most well-known genes that can mutate and raise the risk of breast and/or ovarian cancer are BRCA1, BRCA2, and PALB2. Women who inherit a harmful mutation, or abnormal change, in any of these genes — from their mothers or their fathers — have a much higher-than-average risk of developing breast cancer and/or ovarian cancer. Men with these mutations have an increased risk of breast cancer, especially if the BRCA2 gene is affected, and possibly of prostate cancer. Many inherited cases of breast cancer have been associated with mutations in these three genes.
The function of the BRCA and PALB2 genes is to keep breast cells growing normally and prevent any cancer cell growth. But when these genes contain mutations that are passed from generation to generation, they do not function normally and breast cancer risk increases. Abnormal BRCA1, BRCA2, and PALB2 genes may account for up to 10% of all breast cancers, or 1 out of every 10 cases.
About this study
The researchers conducted genetic testing on 1,201 young adults age 18 to 39 who had been diagnosed with cancer between 2015 and 2019 at Memorial Sloan Kettering Cancer Center. The genetic test looked for mutations in 88 genes known to be linked to a higher risk of cancer.
Of the people in the study:
- 877 were diagnosed with early-onset cancer; the most common diagnoses were colorectal, breast, kidney, pancreatic, and ovarian cancer; specifically, 342 people were diagnosed with breast cancer
- 324 people had young-adult cancer; the most common diagnoses were sarcoma (cancer that starts in the soft tissue or bones), brain, testicular, and thyroid cancer
Inherited genetic mutations were found in:
- 21% of people diagnosed with early-onset cancer
- 13% of people diagnosed with young-adult cancer
Among people diagnosed with early-onset cancer, the highest rates of genetic mutations were found in people diagnosed with pancreas, breast, and kidney cancer.
The most frequent mutations were found in the:
- BRCA1 gene
- BRCA2 gene
- ATM gene
- CHEK2 gene
- the genes linked to Lynch syndrome, including MLH1, MSH2, MSH6, PMS2, and EPCAM
“Here, the surprising finding is that the germline prevalence of these mutations is significantly higher than we had previously thought,” commented Elaine Mardis, Ph.D., co-executive director of the Steve and Cindy Rasmussen Institute for Genomic Medicine at Nationwide Children’s Hospital and past president of the American Association for Cancer Research, who was one of the moderators of a media briefing on the research.
“The distinct set of germline variants appear to suggest that patients with early-onset cancers harbor mutations similar to those also found in older individuals with cancer, but at a higher prevalence,” Stadler said. “Our results suggest that among patients with early-onset cancers, the increased prevalence of germline mutations support a role for genetic testing irrespective of tumor type.”
What this means for you
If you’ve been diagnosed with breast cancer and are 18 to 39 years old, you are considered to have early-onset cancer. The results of this study suggest that genetic testing may help you find out if you have a mutation linked to a higher risk of breast or another type of cancer.
Knowing you have a genetic mutation may influence your treatment and long-term screening decisions, as well as help you identify any family members who also may be at high risk for having a genetic mutation linked to breast cancer:
- Women who have a BRCA1 or BRCA2 mutation can benefit from a class of medicines called PARP inhibitors. Two PARP inhibitors are approved to treat BRCA1- and BRCA2-associated metastatic breast cancer.
- Anyone with a genetic mutation linked to breast cancer has a higher risk of a second cancer, so more frequent screening is usually recommended.
- If a person has a genetic mutation, every first-degree relative — sisters, brothers, sons, and daughters — has a 50% risk of having the same mutation. Having this knowledge can allow for enhanced screening and prevention steps for loved ones who also may have the mutation.
So if you’ve been diagnosed with early-onset breast cancer, you may want to talk to your doctor or a licensed certified genetic counselor about your diagnosis and ask if having a genetic test makes sense for you. A licensed certified genetic counselor or your doctor can help you understand the test and accurately interpret the results.
For more information on genetic testing, including types of genetic tests and how results are reported, visit the Breastcancer.org Genetic Testing pages.
For more information on genes and genetic mutations linked to breast cancer, as well as all the risk-lowering steps you can take if you have a genetic mutation, visit the Breast Cancer Risk Factors: Genetics page in the Breastcancer.org Lower Your Risk section.
If you've tested positive for a mutation linked to breast cancer and would like to talk about this with others who have also tested positive, join the Breastcancer.org Discussion Board forum Positive Genetic Test Results.
Written by: Jamie DePolo, senior editor
Reviewed by: Brian Wojciechowski, M.D., medical adviser
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