Late rectal sequelae following definitive radiation therapy for carcinoma of the uterine cervix: A dosimetric analysis

Purpose : This study attempted to correlate patient, treatment, and dosimetric factors with the risk of late rectal sequelae in patients treated with radiation therapy (RT) for cervical carcinoma. Methods and Materials : A total of 183 patients with cervical carcinoma (67 Stage I, 93 Stage II, and 23 Stage III) treated with definitive RT with a minimum of 2 years follow-up evaluated. Treatment consisted of external beam pelvic RT (EBRT) followed by intracavitary RT (ICRT) consisting of one or two insertions. Complications were scored and analyzed as a function of 25 patients and treatment factors. Conventional total rectal doses were obtained by adding together the EBRT and ICRT rectal doses. To account for differences in dose rate between the ICRT and EBRT, and variations in EBRT fractionation schemes, biologically equivalent rectal doses (BED) were calculated using a linear quadratic model. In addition, the influence of the varying proportions of EBRT and ICRT rectal doses were evaluated. Results : Twenty-eight patients (15.3%) developed late rectal sequelae (13 Grade 1, 3 Grade 2, and 12 Grade 3). Diabetes ( p = 0.03), Point A dose ( p = 0.04), and conventional EBRT dose ( p = 0.03) were the most significant factors ob multivariate analysis. Logistic regression analysis demonstrated a low risk (