Stereotactic Body Radiosurgery using Volumetric Arc Therapy as an alternative to High Dose Rate Brachytherapy Boost in Gynecological Cancer

Abstract

Background: The purpose of this study was to determine if stereotactic body radiosurgery (SBRT) using volumetric modulated arc therapy (VMAT) can be used to deliver a boost to the vaginal cuff in patients with gynecological cancer as an alternative to high dose rate (HDR) brachytherapy. Methods: Between January and July 2009, five patients with gynecological cancer were treated with postoperative radiation therapy to the whole pelvis with doses ranging from 41.4 Gy to 45 Gy. This was followed with a boost to the vaginal cuff with SBRT using VMAT. The total dose delivered in the boost ranged from 9 Gy to 21 Gy given in three fractions. Plan comparisons between SBRT with VMAT and HDR were performed for each patient. Results: After three years follow up (range 36 - 43 months), four of five patients (80%) are alive and well, except for one who expired of intercurrent disease after two years. Mild acute toxicity was seen in two out of five patients (40%). No chronic toxicity has been encountered. The dose coverage to the vaginal cuff using either HDR or VMAT was similar; however, the VMAT plan provided superior dose uniformity throughout the target, as well as better sparing of the bladder and the rectum at the mid to high dose levels. Conclusions: In this case review, target coverage, tolerance, and toxicity using SBRT with VMAT as a boost to the vaginal cuff were comparable to HDR brachytherapy. This technique could be considered as a potential alternative to HDR brachytherapy.