Dose received by external genital organs during preoperative radiotherapy for rectal cancer patients

Abstract

Introduction: Preoperative radiotherapy, followed by surgery, is a commonly used approach for locally advanced rectal and colorectal cancer. The external genitalia receive a certain dose of radiation, which may be attributed to long-term sexual dysfunction in these patients. The aim of this study is to find out the dose received by external genital organs in rectal cancer patients receiving preoperative radiotherapy. Materials and Methods: Retrospectively 25 computed tomography (CT) sets of consecutive rectal cancer patients who received preoperative radiotherapy were included. External genital organ contouring was done as per the proposed guidelines given by Brooks et al. Standard radiotherapy plans with three-field wedged portal were run in all the CT sets using 6 MV photons in eclipse treatment planning system (TPS). The total dose prescribed was 50.4 Gy in 28 daily fractions. Dose received by external genitalia were recorded. Results: Various dose-volume histogram (DVH) parameters relating to the dose received by the genitalia were recorded. In the case of male patients, there was no statistically significant difference of values in between supine and prone position except for V40 (%), P = 0.027. In the case of female patients, various DVH values are almost the same in both supine and prone positions (P > 0.05). Conclusion: External genital organs receive a significant radiation dose when treated with standard three-field wedged technique. Therefore, we suggest that the young, sexually active patients may be treated with better conformal techniques to reduce the radiation dose received by the external genitals as low as possible.