Background: Several epidemiologic studies have shown an inverse relationship between parity and the incidence of endometrial carcinoma. A prognostic influence of reproductive factors has been reported for carcinomas of the breast and uterine cervix; but no such independent influence has been reported for endometrial carcinoma, to the authors' knowledge. Therefore, the authors investigated the prognostic importance of parity in an unselected group of patients.
Methods: Clinical and histopathologic data on all 316 patients treated for endometrial carcinoma during the period 1981-1990 in Hordaland County, Norway, were related to cause specific death in univariate (Kaplan-Meier) and multivariate (Cox proportional hazards regression model) analyses. The median follow-up for the survivors was 9 years (range, 4-16 years). No patients were lost due to insufficient follow-up information.
Results: Nulliparous women had a poorer 5-year survival rate compared with patients who had had 1 or more deliveries (57% vs. 81%, P = 0.0001), and they were significantly older and had more advanced disease at the time of primary surgery than the parous women. After adjustment for traditional risk factors, a hazard ratio of 2.81 (95% confidence interval, 1.55-5.06) was found for nulliparous versus parous women. International Federation of Gynecology and Obstetrics stage, curative treatment, and tumor differentiation grade were also identified as independent prognostic factors, whereas age and menopausal status had prognostic significance in the univariate analysis only.
Conclusions: The decreased survival among nulliparous women reported herein may reflect biologic differences between parous and nulliparous endometrial carcinoma patients. It may also be due in part to a greater delay in diagnosing the women in the nulliparous group.