Relationships of uterine and ovarian tumors to pre-existing chronic conditions

Objective: Several chronic diseases have been hypothesized to affect the risk of subsequent gynecologic malignancies, possibly through shared hormonal mechanisms. Methods: Using record linkage techniques, we assessed the relationships between hospital and outpatient admissions for gallbladder disease, diabetes, hypertension, thyroid diseases and obesity and the subsequent development of uterine and ovarian cancers in Denmark between 1978 and 1998. Based on a subsample of more than 99,000 women, including 1398 uterine and 2491 ovarian cancers, we derived relative risks (RRs) and 95% confidence intervals (CIs) associated with overall and histology-specific cancer risks after adjustment for age, calendar time and reproductive characteristics. Results: Uterine cancers were related to previous diagnoses of thyroid diseases (RR = 1.52, 95% CI 1.17-1.98) and obesity (2.05, 1.40-3.00). Associations with diabetes were confounded by obesity, but there were some elevations in risk for subjects diagnosed with obesity prior to age 45 (RRs 1.66-1.79). Although the "usual types" of endometrial cancer largely accounted for the observed associations, there was some evidence that uterine sarcomas (n = 137) were related to prior diagnoses of thyroid diseases (2.78, 1.41-5.50). In contrast, ovarian cancers were not strongly related to most documented chronic diseases. Serous carcinomas were associated with gallbladder diseases of short durations, but detection bias or misdiagnosis probably accounts for this association. An association of obesity and endometrioid ovarian cancer was not identified. Conclusions: Uterine cancers, including sarcomas, appear to be influenced by selected chronic diseases. Further attention should focus on possible biologic mechanisms underlying observed associations with thyroid diseases and obesity.