November is Prostate Cancer Awareness Month so we would like to share some genetic information. You can learn more about the basic concepts of hereditary cancer by reading our notre article on the subject.
1 in 9 men (11%) will develop prostate cancer in their lifetime and the diagnosis usually occurs between 65 and 74 years old. That said, a large majority of these cancers, around 75% [1]are detected at an early stage and are found only in the prostate, these are called localized cancer. For most of these cases, the cancer grows slowly and has little or no effect on life expectancy.
The Impact of Family History
Several studies have shown that the risk of developing prostate cancer is higher if other family members have been diagnosed with this type of cancer. For example, a man whose father or brother has prostate cancer is two to three times more likely to develop prostate cancer. The risks are higher if the relatives were diagnosed before the age of 60.
What about cancer predisposition genes?
Between 5 and 10% of prostate cancer cases are associated with a genetic predisposition. Genes predisposing to hereditary cancer are more frequently identified (11.8%) in metastatic cancers, i.e. the cancer has spread to other organs, than in localized cancers (4.6% with identified genes).[2]
Several genes have been associated with prostate cancer but the most common are BRCA2, ATM, CHEK2 and BRCA1. The genes associated with Lynch syndrome (associated with colorectal cancer and other types of cancer) are also possibly linked to an increased risk of prostate cancer.
What is the link between prostate cancer in men and breast cancer in women?
Several of the genes associated with prostate cancer are genes known for hereditary breast cancer predispositions, such as BRCA1 and BRCA2. When trying to determine the risks of hereditary cancer, it is therefore important to provide information regarding men diagnosed with prostate cancer and women diagnosed with breast or ovarian cancer.
Why consider a genetic test?
A male carrier will have access to different screening options than those offered to the general population. For example, it is recommended that men with BRCA2 start screening at age 40. Therefore, if cancer develops, there is a better chance of detecting it at an early stage.
A man who is not a carrier of the pathogenic variant already known to his family does not have an increased risk of cancer despite the family history and can follow the screening recommendations for the general population.
Identifying the presence of a cancer predisposing gene can help other family members know their risk of developing certain types of cancer and have access to screening options at a younger age.
Targeted Treatments
One of our previous articles was about precision medicine and targeted treatments. According to specific criteria, some men with prostate cancer carrying a BRCA1, BRCA2 or ATM variant (or when the tumour contains a variant of one of these genes), are eligible for targeted treatment options such as Parp inhibitors.
Ressources :
If you want to learn more about prostate cancer, including about screening, impacts and treatments, visit the Procure website.
If you have any questions or concerns about the risk of prostate cancer in relation to your family history, don’t hesitate to discuss this with your physician. He may refer you to a genetic department where you can meet a genetic counsellor who will assess your risks, determine if you are eligible for genetic testing, and discuss your options.
Nathalie Bolduc, MSc, CGAC, CGC
Certified genetic counselor
Références
[1] National Cancer Institute, SEER – Surveillance, Epidemiology and End Results Program. Cancer Stat Facts: Prostate Cancer. https://seer.cancer.gov/statfacts/html/prost.html
[2] Inherited DNA-Repair Gene Mutations in Men with Metastatic Prostate Cancer, Pritchard et al, 2016, N Engl J Med 2016; 375:443-453 DOI: 10.1056/NEJMoa1603144. https://www.nejm.org/doi/full/10.1056/NEJMoa1603144