Safety of adjuvant intensity-modulated postoperative radiation therapy in endometrial cancer: Clinical data and dosimetric parameters according to the International Commission on Radiation Units (ICRU) 83 report.

Aim: To report a single-institution experience using postoperative pelvic Intensity Modulation Radiation Therapy (IMRT) using tomotherapy accelerators (TA) in postoperative endometrial cancer (EC) regarding ICRU 83 recommendations.

Background: IMRT in gynecological malignancies provides excellent dosimetric data, lower rates of adverse events and clinical data similar to historical series.

Material And Methods: Seventy-six patients with EC were postoperatively treated with adjuvant IMRT using TA. The IMRT dose was 45 Gy for patients without positive lymph nodes and Type I histology and 50.4 Gy for patients with positive lymph nodes and/or type II histology.

Results: With a median follow-up of 29 months, the 12- and 24-month Overall Survival (OS) and Disease-Free Survival (DFS) were 96%, 93%, 87%, and 74%, respectively. Age of less than 60 years was associated with better OS (HR: 8.9; CI: 1.1-68) and DFS (HR: 3.5; CI: 1.2-10.2). Patients with Type II and Type I Grade III histology had a worse OS (HR: 3.3; CI: 1.1-11). Five women (6.6%) presented in-field local vaginal recurrence, 2 (2.6%) presented non-in-field vaginal recurrence, 4 (5.2%) presented pelvic node and distant recurrence and 11 (14.4%) presented only distant metastases. One patient stopped radiation treatment due to Grade III acute diarrhea. No Grade III late toxicity was observed. Planning Target Volume (PTV) coverage showed mean D2, D50, D95, and D98 of 51.64-46.23 Gy, 49.49-44.97 Gy, 48.62-43.96 Gy, and 48.47-43.58 Gy for patients who received 45 and 50.4 Gy, respectively.

Conclusions: IMRT with TA in postoperative EC shows excellent conformity and homogeneity of PTV dose. Without Grade III late toxicity, data from this cohort demonstrated the utility of IMRT.