Over the past 20 years, the proportion of deaths from ovarian cancer has remained high, at 70% of cases diagnosed. A major reason why ovarian cancer has such a poor survival rate is that the most common and deadly type, HGSC, is usually diagnosed at an advanced stage when the cancer has already spread throughout the body. Advanced HGSC can be treated initially but most often comes back in a few years and eventually stops responding to treatment. Because we know that screening is not effective at detecting the cancer at an early stage, prevention is the best way to reduce the number of women dying from this disease.
The risk of developing ovarian cancer is very high in women who have mutations in the BRCA1 or BRCA2 genes and several other risk factors. However if mutations are detected through genetic testing before the cancer develops, ovarian cancer can be prevented by surgically removing the ovaries and fallopian tubes in a procedure called risk-reducing salpingo-oophorectomy. After this relatively simple surgery, the risk of ovarian cancer in women with BRCA1 or BRCA2 gene mutations decreases to approximately the same level as women without mutations in the BRCA1 or BRCA2 genes. We are also studying whether simply removing the fallopian tubes alone is sufficient for reducing cancer because this would allow a woman to keep her ovaries if she still wanted to have children.
Picture this: out of 100 women with an inherited mutation in the BRCA1 or BRCA2 genes, 40 would be expected to develop ovarian cancer during their lifetime (this is also described as a 40% lifetime risk). But if risk-reducing surgery was performed on all 100 of these women, we could prevent ovarian cancer in 36 of these women.
In addition to ovarian cancer, women with BRCA1 or BRCA2 gene mutations are at an increased risk for breast cancer (up to 70% lifetime risk). If risk-reducing salpingo-oophorectomy is performed prior to menopause, the risk for breast cancer is decreased by 50%. This is because the growth of some breast cancers depends on hormones produced by the pre-menopausal ovary. Click to learn more about breast cancer.