Xerostomia and clinical outcomes in definitive intensity modulated radiotherapy (IMRT) versus three-dimensional conformal radiotherapy (3D-CRT) for head and neck squamous cell carcinoma: a meta-analysis

BACKGROUND/AIM: Intensity modulated radiotherapy (IMRT) has been compared with three-dimensional conformal radiotherapy (3D-CRT) in randomized clinical trials for head and neck squamous cell carcinoma (HNSCC). The aim of this meta-analysis was to evaluate the efficacy and toxicity of IMRT and 3D-CRT and identify differences in grade ≥2 xerostomia incidence and clinical outcomes. MATERIALS AND METHODS: The preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement was applied. Random-effects models were used. Primary endpoint was xerostomia of grade 2 or worse. Secondary endpoints were overall survival (OS) and loco-regional control (LRC). RESULTS: Three randomized clinical trials representing 213 patients were identified. Global, grade ≥2 acute xerostomia and late xerostomia at 1 and 2 years after treatment were reduced with the IMRT technique (RR=0.71, 95%CI=0.59-0.86, RR=0.45, 95%CI=0.31-0.65 and RR=0.26, 95%CI=0.15-0.46, respectively). IMRT was not associated with significant OS and LRC improvement compared with 3D-CRT, with OR of 0.70 (95%CI=0.39-1.24; p=0.22) and 1.50 (95%CI=0.75-2.98; p=0.25). CONCLUSION: This meta-analysis explored the value of IMRT compared to 3D-CRT and confirmed the superiority of IMRT over 3D-CRT in terms of grade ≥2 xerostomia rates, but not on clinical outcomes. Its positive impact on tumor control and survival remains to be proven.