Dosimetric comparison of volumetric-modulated arc therapy and intensity-modulated radiation therapy in patients with cervical cancer: a meta-analysis

BACKGROUND: Intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) are two of the main treatment techniques for cervical cancer. Whether either technique significantly reduces irradiated volumes of organs at risk (OARs) remains controversial. The aim of this study was to explore which of these treatment paradigms is the superior technique in cervical treatment, taking clinical outcomes and treatment efficiency from published findings into consideration. MATERIALS AND METHODS: PubMed, EMBASE, and Cochrane Library databases were utilized. The average percent irradiated volumes of OAR were extracted from all included studies. Dual arc results were extracted due to their superiority to single arc methods in terms of plan quality. Standard mean deviations and 95% CIs were calculated for delivery time, monitor units, and average percent irradiated volumes of OAR. Assessment of publication bias and sensitivity analyses were performed. All statistical analyses were conducted using R 3.5.0 software. RESULTS: Eight studies were included in this meta-analysis. For irradiated volumes of OARs, irradiated volume of rectum receiving 40 Gy (rectum V40) was significantly decreased in VMAT compared with IMRT. However, no significant differences were observed between IMRT and VMAT plans in bladder V40 or small bowel V40/V30. In addition, delivery times and monitor units were significantly lower in the VMAT plan than in the IMRT plan. CONCLUSION: Compared with IMRT, VMAT is significantly more protective for the rectum, suggesting that it may be an optional therapy technique for patients with cervical cancer.