Dr. Heidi Gray describes ovarian cancer biology and facts. Ovarian cancer is the 2nd most common gynecologic cancer in the United States, affecting 22,000 - 25,000 women annually. It is less common than other forms of cancer such as breast cancer, but is difficult to treat as it is often diagnosed at a later stage where it has spread outside the ovary. There are not a lot of known risk factors, but approximately 15-20% of ovarian cancer cases are caused by a genetic mutation passed down in families. All women diagnosed with ovarian cancer should undergo genetic counseling and testing for the two most common genetic mutations, BRCA1 and BRCA2 mutations.