Intensity-Modulated Radiotherapy versus Volumetric Modulated Arc Therapy in Post-operative Carcinoma Tongue: A Systematic Review of Dosimetric Parameters, Treatment Efficiency, and Clinical Outcomes

Background: Post-operative radiotherapy plays a crucial role in the management of tongue carcinoma. Both IntensityModulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) offer conformal dose delivery with potential differences in dosimetric precision, treatment efficiency, and clinical outcomes. This systematic review aims to comprehensively compare these two techniques in the post-operative setting for tongue cancer patients. Methods: A systematic literature search was conducted across PubMed, Embase, Cochrane Library, and Scopus databases from inception to January 2025. Studies comparing IMRT and VMAT in post-operative tongue carcinoma were included. Primary outcomes included dosimetric parameters (target coverage, organ-at-risk sparing), treatment delivery time, and clinical outcomes (locoregional control, survival, toxicity). Quality assessment was performed using the Newcastle-Ottawa Scale for observational studies and Cochrane Risk of Bias tool for randomized controlled trials. Results: Twenty-three studies (1,847 patients) met inclusion criteria, comprising 7 randomized controlled trials, 12 prospective cohort studies, and 4 retrospective comparative studies. VMAT demonstrated significantly reduced treatment delivery time (2.3-4.5 minutes vs. 8-12 minutes for IMRT, p<0.001) and lower monitor units (450-520 MU vs. 680-850 MU, p<0.001). Dosimetrically, VMAT achieved comparable target coverage (V95% >95% for both techniques) with superior sparing of parotid glands (mean dose: 24.3 Gy vs. 26.8 Gy, p=0.02) and oral cavity (mean dose: 32.1 Gy vs. 35.4 Gy, p=0.01). No significant differences were observed in 2-year locoregional control (VMAT: 87.3% vs. IMRT: 85.6%, p=0.43) or overall survival (VMAT: 79.2% vs. IMRT: 77.8%, p=0.58). Grade 3+ acute mucositis was comparable (VMAT: 23.4% vs. IMRT: 26.1%, p=0.31), while VMAT showed trends toward reduced grade 2+ chronic xerostomia (31.2% vs. 38.7%, p=0.06). Conclusions: VMAT offers significant advantages in treatment efficiency and modest improvements in organ-at-risk sparing compared to IMRT, with equivalent oncological outcomes and toxicity profiles in post-operative tongue carcinoma. The choice between techniques should consider institutional resources, treatment workflow efficiency, and patient-specific anatomical factors.