Volumetric-modulated arc therapy with vaginal cuff simultaneous integrated boost as an alternative to brachytherapy in adjuvant irradiation for endometrial cancer: a prospective study

Aim: To report preliminary results of a prospective study using pelvic volumetric-modulated arc therapy and simultaneous integrated boost (SIB-VMAT) on vaginal cuff postoperatively in patients with endometrial cancer (EC).

Patients and methods: Fifty consecutive patients, submitted surgery for EC, were recruited to SIB-VMAT prescribing a dose of 54 Gy to the pelvis and 66 Gy to the vaginal cuff in 30 fractions. A 2 mm transvaginal probe and magnetic resonance imaging were used to define the vaginal cuff. Toxicity data were collected according to Common Terminology Criteria for Adverse Events v4.0; clinical outcomes were analyzed.

Results: The median follow-up was 26 (range=12 to 39) months. According to International Federation of Gynecology and Obstetrics 2009, the stages were: IB1 in 20%, IB2 in 28%, IIA2 in 16%, IIB in 6%, IIIA in 2%, and IIIC in 28%. The 2-year Overall Survival and Local Control were 96% and 100%, respectively. Two pelvic node failures were registered. Acute gastrointestinal toxicity was: G0 in 12%, G1 in 52%, G2 in 36%; no case of toxicity G3 or more was observed. Acute genitourinary toxicity was: G0 in 10%, G1 in 42%, G2 in 48%; no case of toxicity G3 or more was observed. No late severe gastrointestinal or genitourinary toxicities were reported. A statistical correlation was found between acute G2 gastrointestinal toxicity with bowel V20 Gy ≥ 30%, V20 ≥ 40%, V30 ≥ 30%, Dmax ≥ 45 Gy. Acute G2 genitourinary toxicity was threefold higher with chemotherapy.

Conclusion: In patients with EC, SIB-VMAT is feasible, and well tolerated. Preliminary data of clinical outcome are promising. Further prospective studies are advocated.