Hyperestrogenism: A relevant risk factor for the development of cancer from endometriosis

Objective. Endometriosis is extremely common in developed countries. Obesit y is a major health concern and may cause hyperestrogenism. Hormonal replac ement, particularly unopposed estrogens after hysterectomy, is becoming pop ular. Because endometriosis is ectopic endometrium, hyperestrogenism (eithe r endogenous or exogenous) may cause hyperplasia or transformation into can cer. This study was conducted to describe the main clinical and pathologic features of malignancies in endometriosis and define the treatment and outc ome and to compare patients who had cancer arising in endometriosis with pa tients who had endometriosis but no cancer. Methods. Patients who had tumors from endometriosis diagnosed from 1986 to 1997 were analyzed retrospectively. Each patient was matched with two contr ol patients (endometriosis without cancer) treated during the same study in terval. Clinical and epidemiologic variables were compared to identify risk factors for the development of cancer. Result. We identified 31 patients with cancer developing from endometriosis . Fifteen women were obese, 9 had a history of endometriosis, and 9 were ta king unopposed estrogen. Endometrioid adenocarcinoma was the most common hi stologic type (16 patients). When the patients with cancer were compared wi th controls, no significantly higher risk for the development of cancer was found with prolonged use of unopposed estrogens or with higher body mass i ndex, but a trend was observed. When obesity and use of unopposed estrogens were considered together, the difference was statistically significant (P = 0.05). Conclusion. Hyperestrogenism, either endogenous or exogenous, is a signific ant risk factor for the development of cancer from endometriosis. The preva lences of endometriosis, obesity, and use of hormonal replacement therapy i n women in developed countries are increasing, and this trend justifies the assumption that cancer developing in endometriosis might become more commo n in the future. (C) 2000 Academic Press.