What Is the Connection between Breast and Ovarian Cancer?

Some forms of breast and ovarian cancer, around five to ten percent of all cases, have a genetic link, and the same genes are responsible for both forms of cancer. In other cases, similar risk factors can be involved, while the bulk of breast and ovarian cancer cases have no specific link. Careful screening for cancer risks can determine which patients may benefit from closer monitoring to identify early warning signs of cancer so they can get treatment as quickly as possible.

In cases where there is a connection between breast and ovarian cancer, the patient has a mutation on either the BRCA1 or BRCA2 gene. In healthy individuals, these genes act as tumor suppressors to limit uncontrolled cell growth. In people with a defective copy of this gene, it doesn't work properly, and that person can be at increased risk for cancer. The pattern of inheritance is dominant, so the patient only needs one defective gene.

Variations and defects in these genes do not automatically mean a patient will get cancer, but they can increase the risk. Both BRCA1 and 2 are associated with higher risks of breast and ovarian cancer, reflecting the connections between these two types of tissue. The cancers that develop in such patients also tend to behave differently from other kinds of cancer and may not respond to treatment in the same way. For this reason, a doctor may recommend genetic testing for a patient with a cancer diagnosis, to develop the most appropriate and effective treatment for her needs.

Some risk factors for breast and ovarian cancer are the same, even in patients with no genetic susceptibility for cancer. Patients who need hormone replacement therapy, especially when it is estrogen-only, with no progesterone, are at increased risk. Some research suggests having a child can decrease risks, and there may be some dietary factors as well. Measures that people take to prevent breast cancer will also help reduce the incidence of ovarian cancer, and vice versa.

Patients with concerns about breast and ovarian cancer can discuss them with their doctors. In someone with a family history of either cancer, it can be a good idea to get a genetic test to check for cancer susceptibility. Testing in the rest of the family can help the doctor trace the pattern of inheritance, and people who do have positive tests may want to consider discussing the issue with genetic relatives so they can decide if they want testing or any additional screening measures.