Increased ovarian cancer risk not linked to cancer family history

Women with a strong family history of breast cancer but who don't have breast cancer genetic mutations can now be reassured that they are not at increased risk for ovarian cancer, according to a new study by researchers at Memorial Sloan-Kettering Cancer Center (MSKCC).

The work, published in the September 21, 2005, issue of the Journal of the National Cancer Institute, is one of the first prospective studies to allow doctors to tailor ovarian cancer screening recommendations for women with a family history of breast cancer but with no identifiable BRCA mutation.

In the ten years since the discovery of BRCA1 and BRCA2 genes, it has been learned that the risk for ovarian cancer in families with mutations in these genes is increased 6- to 61-fold. However, it has also emerged that up to half of families with multiple cases of breast cancer do not have mutations in either BRCA1 or BRCA2. Up until the current study, there has been limited data with which to inform such families as to their risk for ovarian cancer.

The MSKCC Clinical Genetics Service studied 199 families with multiple cases of breast cancer but no identified BRCA mutation. During follow-up, 19 new cases of breast cancer were diagnosed – three times more than the six cases that were expected. Only one case of ovarian cancer was diagnosed, which is what researchers would have anticipated in an average risk population.

While the authors conclude that women from these families do not have an increased risk of ovarian cancer, they also indicate that the genetic mechanism for up to half of hereditary breast cancer remains unknown. Ongoing research at MSKCC, in collaboration with other scientists in the US, Canada, and Israel, is underway to map undiscovered genes associated with hereditary breast cancer.