Effect of body mass index on normal tissue radiation doses and adverse reactions in brachytherapy for cervical cancer / 中华放射肿瘤学杂志

ABSTRACT

Objective:To explore the influence of body mass index (BMI) changes on the doses to normal tissues and adverse reactions of the lower digestive system and urinary system in the brachytherapy for cervical cancer.Methods:Clinical data of 80 cervical cancer patients who received radical radiotherapy in our hospital from January 2020 to February 2021 were retrospectively analyzed. All patients received external beam radiation ± chemotherapy + brachytherapy. The delineation method of target areas and organs at risk (OAR) was determined based on the recommended scheme of GEC-ESTRO. The target areas included high risk (HR)-CTV and intermediate risk (IR)-CTV, and OAR consisted of rectum, sigmoid colon, bladder, and small intestine. The target area dose was evaluated by D 90% of the HR-CTV. The OAR volume dose was evaluated by using D2cm3. Correlation analysis was used to compare the dosimetric relationship between BMI and D2cm3, D1cm3 and D0.1cm3 in bladder, rectum, colon and small intestine. Logistic regression analysis was adopted to analyze the risk factors of acute and late adverse reactions in the lower gastrointestinal system and urinary system. Whether BMI was a risk factor was validated. Results:BMI was negatively correlated with the D2cm3, D1cm3 and D0.1cm3 of the small intestine ( P=0.034, 0.024, 0.034), and the correlation coefficients were -0.240, -0.255, and -0.241, respectively. Logistic regression analysis showed that BMI was not a risk factor for the occurrence of acute and late adverse reactions in the lower gastrointestinal system and urinary system. For every 1 Gy increase of D2cm3, D1cm3 and D0.1cm3 in the small intestine, the relative risk of acute adverse reactions in the lower gastrointestinal system was increased by 16.6%, 15.1%,and 12.7%, respectively. Conclusions:In brachytherapy for cervical cancer, there is a negative correlation between BMI and D2cm3, D1cm3 and D0.1cm3 of the small intestine. As the BMI of patients declines, the radiation dose to the small intestine shows an increasing trend, which may increase the risk of acute adverse reactions in the lower gastrointestinal system.