Methods: The epidemiologic features of 50 women with extraovarian primary peritoneal carcinoma were compared with those of 503 women with primary epithelial ovarian cancer. We included all women with the respective diagnoses admitted to the Roswell Park Cancer Institute between October 1982 and October 1996 who returned an epidemiologic questionnaire. Epidemiologic features of the study and control groups were extracted from a database compiled from a self-administered questionnaire that has been given to patients as part of the admission process since 1982. Individual variables between the study and control groups were compared using Student t test, χ² analysis, and Wilcoxon nonparametric test. Two-tailed P < .05 was considered significant.

Results: We found few significantly different epidemiologic features between women with extraovarian primary peritoneal carcinoma and those with primary epithelial ovarian cancer. Women with extraovarian primary peritoneal carcinoma were significantly older (mean age 63.8 versus 55.0 years, P < .001), had later menarche (13.3 versus 12.8 years, P = .024), and were less likely to have used perineal talc powder (26.0% versus 48.1%, P = .003). There were no significant differences with respect to reproductive history, contraceptive use, or use of hormone replacement therapy. A larger proportion of ovarian cancer patients reported a family history of breast cancer, but the numbers were too small to reach statistical significance.

Conclusion: The epidemiologic features of women with extraovarian primary peritoneal carcinoma compared with women with primary epithelial ovarian cancer show few differences. The observed areas of difference warrant further research to determine whether they suggest the occurrence of distinct disease entities.