Second primary uterine malignancies after radiation therapy for cervical cancer

Radiation exposure has long been established as a risk factor for cancer development. The purpose of this study is to assess the risk of uterine malignancy in patients previously treated for cervical cancer with radiation therapy.

A population-based cohort of 9092 patients diagnosed with cervical cancer who did not undergo surgery and received radiation therapy between 1973 and 2008 was identified from the Surveillance, Epidemiology and End Results Program database (SEER 9). Patients in this cohort who developed endometrial cancer after treatment of cervical cancer were identified. 55,140 patients with endometrial cancer were also identified. The distribution of the different histologic types of endometrial cancer was determined for each of these cohorts.

54 patients (0.6%) were diagnosed with an endometrial cancer more than 12 months after diagnosis of cervical cancer. The average latency to endometrial cancer diagnosis was 160 months, with a range of 14-374 months. The average age of cervical cancer diagnosis was 52 years and the average age at subsequent endometrial cancer diagnosis was 66 years. Only 40% of the endometrial cancers diagnosed following treatment of cervical cancer were endometrioid. The majority were clear-cell adenocarcinomas (42%), 9% were carcinosarcomas and 5.5% were leiomyosarcomas. Of the 55,140 endometrial cancer patients in the database, a vast majority were endometrioid adenocarcinomas (91%), and only 2.3% clear-cell adenocarcinoma, 2.3% carcinosarcoma and 0.5% leiomyosarcoma. The difference in histologic type distribution between these two cohorts is highly significant (p < 0.01).

A small proportion of women who receive radiation for cervical cancer go on to develop endometrial cancer. These are predominantly of the more aggressive histologic types when compared to primary endometrial cancers. The latency from cervical cancer diagnosis to endometrial cancer diagnosis is over a decade. In a patient who still has a uterus after receiving pelvic radiation, vaginal bleeding should be investigated.