Not too many people like to talk about their prostate, or screening for prostate cancer, or even if something is wrong with their prostate. The prostate is a small gland about the size of a walnut that produces seminal fluid, which nourishes and transports sperm. The prostate is below the bladder and in front of the rectum. While easily hidden in the male body, it can become a real problem if not functioning correctly.
Prostate cancer is the second leading cause of cancer death in men. Approximately 1 in 9 men will be diagnosed with this cancer during his lifetime. This type of cancer is more likely to develop in older men and in African-American men. While this can be a serious disease, most men diagnosed with prostate cancer do not die from it. The majority of cancers of the prostate are found to be adenocarcinomas, which means the cancer develops in the gland cells, or the cells that make the seminal fluid.
There are various risk factors that can increase a person’s risk to develop these cancers, including age, race/ethnicity, geography, family history, and genetic mutations. It is rare for a man younger than 40 to be diagnosed with prostate cancer with the majority being diagnosed after 65. Cancer of the prostate develops more often in African-American men and less often in Asian-American and Hispanic/Latino men. It is most common in North America, northwestern Europe, Australia, and the Caribbean islands.
Family history is an important component for all cancers, including those affecting the prostate. Having a first degree relative with cancer of this type more than doubles the risk of developing this type of cancer. Approximately 20% of cancer is considered to be familial, or a combination of genetics and environment. While we cannot always identify the genetic component that causes an increased risk for prostate cancer, based on family history a genetic counselor can assess if there appears to be a familial component. Approximately 10% of cancer is considered hereditary, meaning we can identify a genetic component that is being passed down through the generations. Cancer of the prostate is associated with several hereditary gene mutations.
Genetic Causes of Prostate Cancer
The majority of inherited prostate cancers can be linked to mutations in the BRCA genes. Mutations in the BRCA1 and BRCA2 genes are associated with hereditary breast and ovarian cancer syndrome. While this syndrome has increased cancer risks for breast and ovarian cancer in women, it is also associated with an increased risk for cancer in men. There is approximately a 33% risk for prostate cancer, a 5% risk for pancreatic cancer, and 1-7% risk for male breast cancer. If a family is identified with a BRCA gene mutation, each family member has a 50% chance of inheriting that gene change. If a man is found to have a BRCA gene mutation, it is important to discuss these results with his doctor and review the possibility of beginning prostate cancer screening at the age of 40, in addition to clinical breast exams starting at age 35.
Recent advances in cancer genetics have identified a gene called HOXB13 that increases a person’s risk of prostate cancer when a mutation is found. This gene is called a tumor suppressor gene, which means it’s normal role in the body is to keep cells from growing and dividing out of control. If a mutation is found in HOXB13, this gene cannot function properly. At least two different mutations in this gene have been found to be associated with an increased risk of prostate cancer in families, and possibly a more aggressive form of cancer. Each family member would have a 50% chance of inheriting a HOXB13 gene mutation if identified in their family.
Genetic Testing, Prostate Cancer Screening, and Other Measures
There are several additional syndromes and gene mutations that are associated with these cancers. There are many genetic testing options that will test an individual diagnosed with cancer for the various genes and hereditary syndromes associated with the disease. If you or a family member have a diagnosis of prostate cancer, or if you have a family history of cancer and would like to pursue genetic testing, please contact AT-GC to meet with a genetic counselor.