• Myriam Bouchard, Sylvain Nadeau, Luc Gingras, Paul-Emile Raymond, Frédéric Beaulieu, Luc Beaulieu, André Fortin, and Isabelle Germain.
• Département de Radio-oncologie et Centre de Recherche de L'Hôtel-Dieu de Québec, Centre Hospitalier Universitaire de Québec, L'Hôtel-Dieu de Québec, Québec, QC, Canada.
• Int. J. Radiat. Oncol. Biol. Phys. 2008 Aug 1; 71 (5): 1343-50.

PurposeTo assess disease control and acute and chronic toxicity with aperture-based intensity-modulated radiotherapy (AB-IMRT) for postoperative pelvic irradiation of endometrial cancer.Methods And MaterialsBetween January and July 2005, after hysterectomy for endometrial cancer, 15 patients received 45 Gy to the pelvis using AB-IMRT. The AB-IMRT plans were generated by an in-house treatment planning system (Ballista). The AB-IMRT plans were used for treatment and were dosimetrically compared with three other approaches: conventional four-field, enlarged four-field, and beamlet-based IMRT (BB-IMRT). Disease control and toxicity were prospectively recorded and compared with retrospective data from 30 patients treated with a conventional four-field technique.ResultsAt a median follow-up of 27 months (range, 23-30), no relapse was noted among the AB-IMRT group compared with five relapses in the control group (p = 0.1). The characteristics of each group were similar, except for the mean body mass index, timing of brachytherapy, and applicator type used. Patients treated with AB-IMRT experienced more frequent Grade 2 or greater gastrointestinal acute toxicity (87% vs. 53%, p = 0.02). No statistically significant difference was noted between the two groups regarding the incidence or severity of chronic toxicities. AB-IMRT plans significantly improved target coverage (93% vs. 76% of planning target volume receiving 45 Gy for AB-IMRT vs. conventional four-field technique, respectively). The sparing of organs at risk was similar to that of BB-IMRT.ConclusionThe results of our study have shown that AB-IMRT provides excellent disease control with equivalent late toxicity compared with the conventional four-field technique. AB-IMRT provided treatment delivery and quality assurance advantages compared with BB-IMRT and could reduce the risk of second malignancy compared with BB-IMRT.

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