Assessment of relative risk of second primary tumors after ovarian cancer and of the usefulness of double primary cases as a source of material for genetic studies with a cancer registry

Background. It now is accepted that a small proportion of people with certain forms of cancer have a dominantly inherited gene fault that predisposes them to it. This is more likely with an early age at onset or when the person has had multiple primary tumors. Methods. Population-based data from the North West Regional Cancer Registry of England regarding 4157 ovarian cancer cases diagnosed between 1980 and 1989 were analyzed to determine the relative risks (RR) of second primary breast and colorectal carcinomas. Results. Elevated risks approaching significance were observed for breast and colorectal carcinoma subsequent to ovarian cancer. After stratification into groups for ovarian histopathologic characteristics and age at onset, significantly elevated risks were obtained for both breast and colorectal tumors after ovarian carcinoma for women younger than 60 years of age at onset and with serous histopathologic characteristics (breast RR, 2.68, P <0.05; colorectal RR, 4.25, P <0.05). Conclusions. These results emphasize the need for greater awareness of the possibility of development of additional cancer after ovarian carcinoma in high-risk groups. Overall, the study supports the theory that breast, colorectal, and ovarian tumors are related genetically.