[Reproductive activities as risk factors of epithelial ovarian cancer: a case-control epidemiologic study]

A case-control study involving 112 patients with pathologically confirmed epithelial ovarian cancer and 224 randomized community controls matched to the cases on age was conducted in the Metropolitan Beijing Area. The results showed that parity, gravidity and their related factors play an important role in the genesis of epithelial ovarian cancer. A good inverse relationship was observed between the number of full term pregnancies and the magnitude of relative risk. Term pregnancy seemed to have a stronger protective effect than aborted pregnancy and an adequate protection can be achieved by three term pregnancies. At the same time, the number of ovulatory years was positively correlated with the rise of the relative risk. In addition, it was found that age at the first pregnancy was not related to the occurrence of ovarian cancer as indicated in the literature.