Volumetric Modulated Arc Therapy versus Fixed-Field Intensity-Modulated Radiotherapy in Radical Irradiation for Cervical Cancer without Lymphadenectasis: Dosimetric and Clinical Results.

BACKGROUND: The aim of this study was to compare the dosimetric parameters, clinical complications, and efficacy of volumetric modulated arc therapy (VMAT) and fixed-field intensity-modulated radiotherapy (f-IMRT) in radical radiotherapy for cervical cancer without lymphadenectasis.

METHODS: 84 cervical cancer patients undergoing treatment with VMAT and f-IMRT were selected. Dose-volume histograms were used to evaluate the dose distribution in the planning target volume (PTV) and organs at risk. The clinical complications and efficacy were observed.

RESULTS: The homogeneity index (HI) and the conformity index (CI) of VMAT plans were both superior to the HI and CI of f-IMRT plans (p = 0.043, 0.025). VMAT plans resulted in a reduction in the V30 of the rectum and V40 of the bladder (p = 0.002). Furthermore, the monitor units (MUs) for VMAT were less than a quarter of those for f-IMRT. The treatment time for VMAT was less than a half of that for f-IMRT. Both clinical complications and efficacy showed no significant differences.

CONCLUSION: VMAT plans showed superior dose coverage of the PTV, better protection of the rectum and bladder in dosimetry, and significantly reduced MUs and treatment time compared with f-IMRT. Clinical results were similar for both plans.