Less Gastrointestinal Toxicity After Adjuvant Radiotherapy on a Small Pelvic Field Compared to a Standard Pelvic Field in Patients With Endometrial Carcinoma

Objective: Radiotherapy is associated with short-term and long-term morbidity. This study compared toxicity rates among patients with endometrial carcinoma (EC) treated with adjuvant external beam radiation therapy (EBRT) on a small pelvic field (SmPF) in comparison with a standard pelvic field (StPF) or an extended field (EF). Methods: Patients with EC preoperatively diagnosed with high-grade histological disease (grade 3 endometrioid, papillary serous, clear cell, and mixed tumor type) or cervical involvement were treated with total abdominal hysterectomy, bilateral salpingo-oophorectomy, and lymphadenectomy in the University Medical Center Groningen between 1999 and 2008. Patients who received adjuvant EBRT were included in this study. External beam radiation therapy on SmPF (includes only the central pelvis and proximal vagina) was applied in case of negative lymph nodes after adequate lymphadenectomy (>= 10 lymph nodes removed at the bilateral obturator and external iliac nodal stations). In case of positive pelvic lymph nodes or inadequate lymphadenectomy, EBRT on StPF was given. External beam radiation therapy on EF was applied in case of common iliac and/or para-aortic lymph node metastases. Retrospectively, using the Common Terminology Criteria for Adverse Events v3.0, acute toxicity was scored during radiotherapy, whereas late toxicity was scored, from 3 months onward after treatment. Results: Toxicity could be evaluated in 75 patients treated with SmPF (n = 33), StPF (n = 28), and EF EBRT (n = 14). Most patients with late adverse events had also reported toxicity during radiotherapy (71%). The most common late adverse events were gastrointestinal tract related, more frequently present in the StPF group (60.7%) compared to SmPF (33.3%; P = 0.032). In particular, nausea and anorexia were more frequent in the StPF group (32.1%) compared to the SmPF group (3.0%; P = 0.004), as well as ileus (14.3% vs 0%, P = 0.039, respectively). Conclusions: Treatment with adjuvant EBRT on SmPF results in less gastrointestinal late adverse events compared to treatment with EBRT on StPF in patients with surgically staged EC.