Impact of Adjuvant External-Beam Radiation Therapy in Early-Stage Uterine Papillary Serous and Clear Cell Carcinoma

Purpose: Adjuvant radiation therapy (RT) in early-stage high- to intermediate-risk endometrioid adenocarcinoma is well established and has been shown to improve locoregional control. Its role in the management of early-stage clear cell carcinoma and uterine papillary serous carcinoma (UPSC) remains controversial. Methods and Materials: Using the Surveillance Epidemiology and End Results database, we identified women with American Joint Committee on Cancer Stage Sixth Edition. Stage IA–IIB clear cell carcinoma or UPSC who underwent hysterectomy with or without adjuvant RT between 1988 and 2003. We used Kaplan-Meier and Cox regression analysis to compare overall survival (OS) for all patients. Results: We identified 1,333 women of whom 451 had clear cell carcinoma and 882 had UPSC. Of those patients, 775 underwent surgery alone and 558 received adjuvant RT as well. For Stages I–IIB disease, the median OS with surgery alone was 106 months, vs. 151 months with adjuvant RT (p = 0.006). On subgroup analysis, we saw the benefit from adjuvant RT only in Stage IB–C patients. For Stage IB disease, patients undergoing surgery alone had a median OS of 117 months, vs. median survival not reached with the addition of RT (p = 0.006). For Stage IC disease, surgery alone had a median OS of 35 months vs. 120 months with RT (p = 0.001). Although the apparent benefit of RT diminished when measured via multivariate analysis, the impact of RT on survival did show a trend toward significance (hazard ration 0.808, confidence interval 95% 0.651–1.002, p = 0.052) Conclusion: In FIGO Stage IB–C papillary serous and clear cell uterine carcinoma, adjuvant RT seems to play an important role in improving survival.