Less Than Whole Uterus Irradiation for Locally Advanced Cervical Cancer Maintains Locoregional Control and Decreases Radiation Dose to Bowel

Abstract

Objective: This study aimed to evaluate whether our institutional standard of less-than-whole-uterus irradiation affects locoregional control in patients with locally advanced cervical cancer. Methods and Materials: We retrospectively reviewed 53 patients with stage IB to IVB cervical carcinoma who were treated with image guided intensity modulated radiation therapy and brachytherapy. The entire uterus was not included in the clinical target volume, as per our institutional standard. Dosimetric parameters were obtained, including positron emission tomography gross tumor volume (GTV), uterus volume excluding GTV, proportion of uterus included in the planning target volume (PTV; percentage), volume of overlap between uterus and prescription dose (cm 3 ), minimum and mean dose to the uterus, and bowel V40 and D200cc. Local, regional, and distant failure and death were recorded. Results: The median proportion of the uterus included in the PTV was 66%. With a median follow-up of 44 months, no patient experienced isolated local recurrence, and 2-year locoregional failure was 10.9%. Positron emission tomography GTV correlated significantly with increased chance of any failure (P =.049; 95% confidence interval, 1.000-1.018). Compared with patients who had ≥90% of the uterus included in the PTV (n = 12), patients who had <90% (n = 41) of the uterus included in the PTV had significantly lower bowel V40 (P =.049) and D200cc (P =.006). Conclusions: Less-than-whole-uterus irradiation for locally advanced cervical cancer does not compromise locoregional control and reduces bowel V40 and D200cc. Further investigation is required to evaluate whether this reduction in bowel dose translates to a clinically significant reduction in bowel toxicity and whether modifications should be made to the recommended definitive cervix intensity modulated radiation therapy volumes.