Acute radiation dermatitis in endometrial cancer: Intensity-modulated radiotherapy versus volumetric modulated arc therapy

Background Comparative data on acute radiation dermatitis between intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) in postoperative endometrial cancer are limited. The present investigation aimed to assess skin toxicity and dosimetric parameters across these techniques. Methods This retrospective cohort analysis identified individuals with locally advanced endometrial cancer receiving postoperative pelvic radiotherapy from January 2022 to January 2025. Patients were grouped by technique (IMRT or VMAT). Evaluated parameters included planning target volume dosimetric indices, skin dosimetric parameters (V20Gy, V30Gy, mean dose), acute radiation dermatitis severity graded weekly per CTCAE v5.0, small bowel and bladder dose-volume metrics, acute gastrointestinal and genitourinary toxicities, bone marrow dosimetric exposure, hematologic toxicity profiles, and treatment efficiency metrics. Results A total of 148 patients were analyzed (IMRT, 70; VMAT, 78). VMAT achieved superior conformity (0.89 ± 0.03 vs. 0.84 ± 0.04, P < 0.001) and homogeneity (0.07 ± 0.03 vs. 0.10 ± 0.03, P < 0.001). Skin V20Gy (22.17% vs. 23.84%, P = 0.003) and V30Gy (11.26% vs. 12.43%, P = 0.005) were lower with VMAT, corresponding to reduced grade ≥2 dermatitis (11.54% vs. 25.71%, P = 0.026). Small bowel V40Gy (83.03 vs. 87.12 cm 3 , P = 0.006) and acute gastrointestinal reactions (16.67% vs. 32.86%, P = 0.022) favored VMAT. Treatment time was shorter with VMAT (172.44 vs. 365.12 s, P < 0.001). Conclusion These findings suggest that VMAT provides dosimetric advantages and a modest reduction in moderate acute skin toxicity compared with fixed-field IMRT; however, this did not result in a decrease in the use of topical dressings, analgesics, or antibiotics for skin reactions. The clinical benefit therefore appears concentrated in patient-reported comfort and operational efficiency rather than in a lower burden of dermatitis-specific interventions.