Testing For BRCA Gene Mutations: Cancer Risk And Genetics

Several genes other than BRCA1 and BRCA2 have been identified as possibly increasing the risk of breast cancer since 2013.

Given the considerable interest and the number of questions that may arise, we thought we would put together a few quick thoughts and facts on inherited breast cancer, specifically the BRCA1 gene.

Take a look beyond breast cancer

BRCA1 and BRCA2 are sometimes called breast cancer genes. Also associated with them is hereditary ovarian cancer. There is also an increased risk for pancreatic, prostate, and melanoma cancers. Other cancers also have hereditary forms. For example, in Cowden syndrome, the PTEN gene increases cancer risks. A gene mutation in a family will lead to surveillance for all types of cancer associated with that gene.

(Breast) cancer can affect men as well!

BRCA is commonly thought to be a breast cancer gene that doesn't affect men. BRCA gene changes can be inherited equally by males and females. The same is true for other cancer genes. Parents who inherit a gene mutation have a 50% chance of passing it along to their children, and a 50% chance of passing it along without it. Both genders may be at increased risk of developing cancer due to this gene.

Males who inherit mutations in BRCA1 or BRCA2 have a greater lifetime risk of developing breast cancer than the general population of 1%.

Other mutations in hereditary cancer predisposition genes, such as PTEN, CDH1, ATM, and CHEK2, can lead to colon, thyroid, stomach, and pancreatic cancers.

Keep an eye out for these red flags

• Under 50-year-olds who are diagnosed with early-onset cancers

• Cancer of the ovary in the family or personal history

• Men with breast cancer in their family

• The same individual has multiple cancer diagnoses (bilateral breast cancers, uterine and colon cancer)

• Family history of cancer (e.g., breast, ovarian, prostate)

• Several rare cancer types (adrenal cortex cancer, hemangioblastoma, retinoblastoma)

• Multiple generations with early onset or multiple people with cancer

Can genetic testing serve as a proactive tool or is it Pandora's box?

Genetic testing can be intimidating and complex. The question is, how can genetic testing help? Genetic testing can identify cancer gene mutations. Identifying mutations that raise cancer risk can save lives in some cases.

Genetic testing has the following benefits:

• More accurate prediction of cancer risks and types

• The goal is to personalize screenings and management recommendations

• Assist in making treatment decisions

• Other family members can use this information

Tests based on genetic information have limitations:

• We cannot predict when and if cancer will occur from a positive genetic test result.

• Learning that we are predisposed to cancer can increase anxiety.

• Test results may be unexpected or unanticipated. Newly discovered genes often leave us with more questions than answers.

• The risks of some genes are unknown. Limited data on types of cancer and cancer risk make consensus recommendations difficult.

There is no need to feel alone!

A cancer diagnosis can be frightening and isolating. Despite multiple tests, appointments, and decisions that may have to be made, you are not alone on this journey. Cancer runs in many families, which can cause anxiety and fear. Ask your healthcare team any questions you may have, and talk to other cancer support groups and your friends and family members too.

Takeaway

It's not just BRCA1 and BRCA2 that cause hereditary forms of breast and ovarian cancer. In the case of BRCA1 and BRCA2 tests that test negative, your family's cancers may be due to other cancer predisposition genes. Depending on your family history and personal history, you may need further testing or information from a genetic counsellor.