Peritoneal cancer is a rare type of cancer that begins in the peritoneum, a thin layer of tissue lining the inside of the abdomen and covering its organs. This cancer shares many similarities with the most common type of ovarian cancer, including its cellular origin and treatment approaches. Peritoneal cancer often presents with vague symptoms, such as abdominal bloating or pain, which can lead to diagnosis at advanced stages.
The Hereditary Nature of Peritoneal Cancer
While most cases of peritoneal cancer occur sporadically, meaning they arise by chance without a clear inherited cause, a significant portion can be hereditary. This indicates that it is not the cancer itself that is passed down, but rather an inherited predisposition or an increased risk due to specific changes in genes. Individuals with a first-degree family member, such as a mother or sister, who has had peritoneal, fallopian tube, or ovarian cancer face a higher risk. Approximately 15% to 20% of people diagnosed with ovarian, fallopian tube, and primary peritoneal cancer have an inherited gene mutation contributing to their risk.
Genes Linked to Peritoneal Cancer Risk
Specific genes are associated with an increased risk of developing hereditary peritoneal cancer. The BRCA1 and BRCA2 genes are the most well-known, normally functioning in DNA repair to prevent cell damage. Mutations in these genes disrupt this repair process, leading to a higher likelihood of cancer development. Women who inherit harmful changes in BRCA1 or BRCA2 have a significantly increased lifetime risk for ovarian, fallopian tube, and primary peritoneal cancers.
Lynch Syndrome, also known as hereditary nonpolyposis colorectal cancer (HNPCC), also increases the risk of peritoneal cancer. This syndrome is caused by mutations in mismatch repair genes, including MLH1, MSH2, MSH6, PMS2, and EPCAM. These genes are responsible for correcting errors in DNA replication. When mutated, they can lead to an elevated risk not only for colorectal and endometrial cancers but also for ovarian and peritoneal cancers.
Genetic Testing and Its Importance
Genetic testing for cancer risk typically involves analyzing a blood or saliva sample to identify specific gene mutations. Individuals who may be candidates for genetic testing include those with a personal history of peritoneal, ovarian, or related cancers, or those with a strong family history of these cancers, especially if diagnoses occurred at younger ages. Testing is recommended for anyone diagnosed with fallopian tube, ovarian, or primary peritoneal cancer, as about one in four women with these diagnoses will test positive for an inherited mutation.
Identifying a gene mutation through testing can provide crucial information for informing future screening and prevention strategies for the individual. It can also guide treatment decisions if cancer is already present. Genetic counseling, both before and after testing, is an important step to help individuals understand the implications of the results and make informed decisions about their healthcare.
Managing Family Risk
Once a hereditary gene mutation is identified in a family member, “cascade testing” becomes an important strategy for managing risk within the family. Cascade testing involves offering genetic testing to blood relatives of the individual found to carry the mutation. This allows other family members to learn if they also inherited the predisposition, even if they have not yet developed cancer.
For family members identified with an elevated risk, various strategies can be considered to manage that risk. These may include increased surveillance through more frequent screenings or, in some cases, risk-reducing surgical options. Open family communication about genetic test results and cancer history is encouraged. Consulting with healthcare professionals and genetic counselors is important for personalized guidance on risk management and prevention strategies for all at-risk family members.