Survival after radiation therapy for early-stage endometrial carcinoma: The Oslo study revisited after up to 43 years of follow-up.

Abstract

5008 Background: There is an ongoing debate regarding the benefit of radiation in patients with early stage endometrial carcinoma. Data on long time risk conferred by radiation is scarce. This study is a long-term follow-up on survival and secondary cancers of a previously published randomized study (Aalders J. et al., Obstet Gynecol 1980; 56: 419-27). Methods: Between 1968 and 1974, 568 patients with endometrial cancer FIGO stage I primarily treated with abdominal hysterectomy and bilateral salpingo-oophorectomy were included in the study. Patients were postoperatively randomized to receive either vaginal radium brachytherapy followed by external pelvic radiation 40 Gy (N=288) or brachytherapy alone (N=280). Survival data and data on incident secondary cancers were obtained by individual linkage to the Registry of Statistics Norway and Cancer Registry of Norway. By the end of follow-up at 1 November 2011, 45 (7.9%) patients were still alive. We used Cox proportional hazards model to estimate hazard ratios (HR) with 95% confidence intervals (95% CI). We also conducted analyses stratified by age groups. Results: After median 21 (range 0-43.4) years of follow-up there was no significant difference in overall survival or relapse free survival between treatment arms with HR of 1.12 (95% CI: 0.95-1.33) and HR 0.88 (95% CI: 0.55-1.40), respectively. Patients treated with external radiation had significantly lower risk of developing locoregional relapse (p<0.001). However, women younger than 60 years had a significant poorer survival after external radiation (HR 1.36; 95% Cl: 1.06-1.76). In this patient group the risk of secondary cancer was significantly increased (HR 1.9; 95% CI: 1.23-3.03). Conclusions: We observed no survival benefit of external pelvic radiation in early stage endometrial carcinoma. In women younger than 60 years, pelvic radiation decreased survival, probably due to increased risk of subsequent second neoplasms. Adjuvant external radiotherapy cannot be recommended to this patient group. Those who have received such treatment might eventually benefit from prolonged post treatment surveillance with respect to secondary cancer.