Correlation analysis of treatment positions and body mass index on acute radiation enteritis for cervical cancer patients underwent volumetric modulated arc therapy

Purpose: To investigate the correlation of the incidence of acute radiation-induced enteritis with the factors of patient treatment position and body mass index (BMI) in cervical cancer patient treated with the volumetric modulated arc therapy (VMAT) radiotherapy. Methods: 96 patients with cervical cancer underwent VMAT were divided into two groups based on the BMI of the patients: the underweight (<24 kg/m²) group and the overweight (=24 kg/m2 ) group. According to the treatment position during radiotherapy, all patients were divided into two groups: supine position and prone position subgroups. All the patients were further divided into four groups: Group I (prone position with underweight (n =23)), Group II (prone position with overweight (n = 20)), group III (supine position with underweight (n = 40)) and Group IV (supine with overweight (n = 13)). The treatment volumes and normal tissues (e.g., small intestine and rectum) were delineated and confirmed by two senior radiation oncologists. Then, the treatment plans were produced and optimized by the experienced medical physicists. The correlation between the incidence of acute radiation enteritis and the dose volume measurements of the small intestine and rectum was analyzed. Results: Binary logistic analysis showed that the dose parameter of V40 of the rectal was a risk factor for radiation proctitis (p = 0.003), and the univariate receiver operating characteristic (ROC) analysis showed a high area under curve AUC of 0.927 of this parameters for prediction of radiation proctitis. Using the nonparametric Kruskal Wallis test, the treatment position was found to be an important factor in distinguishing radiation enteritis above grade II (p 0.003), whereas the BMI showed no significant role in predicting radiation enteritis above grade II, and there was no interaction effect between treatment position and BMI (p = 0.224). Using stratified Chi-square test, it was found that treatment position and BMI were not high-risk factors for acute radiation proctitis above grade II (P > 0.05). Conclusion: For obese cervical cancer patients underwent VAMT radiotherapy, the prone position was recommended during the beam irradiation, which can significantly reduce the radiation dose to the small intestine. To reduce the incidence of radiation proctitis, it is recommended that the V40 of rectal should be less than 45% as possible through optimizing the treatment plan