Risk factors for developing multiple malignancies in patients with endometrial cancer.

Objective: The purposes of this study were to investigate the clinical and pathologic characteristics of patients with endometrial cancer (EC) and associated breast, colorectal, or ovarian cancer, and to define the risk of developing an associated malignancy during follow-up after EC treatment.

Methods/materials: During a 13-year period, 1028 women had a hysterectomy for EC at our institution and available clinical information. An associated malignancy was defined as diagnosis of another malignant disease before or at the time of operation for EC or during follow-up.

Results: Of these 1028 patients, 208 (20%) had a history of another malignancy besides EC. Most frequent were carcinomas of the breast (10%), colon-rectum (3%), and ovary (4%). Patients with a family history of hereditary nonpolyposis colorectal cancer (HNPCC)-related cancers and presence of EC in the lower uterine segment (LUS) had a higher risk of developing colorectal cancer within 5 years after hysterectomy (2% and 6%, respectively). After multivariate analysis, only LUS involvement remained significantly associated with this risk. Patients with EC and associated ovarian cancer were more likely to be younger and have superficially invasive EC, family history of HNPCC-related tumors, and family history of breast or ovarian cancer. After multivariate analysis, only age younger than 50 years (odds ratio [OR], 4.27; 95% confidence interval [CI], 1.49-12.21) and family history of breast or ovarian cancer (OR, 3.95; 95% CI, 1.60-9.72) were significantly related to risk of having ovarian cancer associated with EC. No significant risk factors were identified for development of an associated breast cancer after EC.

Conclusions: Young age, family history of malignancy, and LUS involvement may indicate the need for more intensive preventive strategies for colorectal cancer and for evaluating the risk of synchronous ovarian cancer in patients with EC.