Evaluation of the toxicity of prophylactic extended-field radiation therapy with volumetric modulated arc therapy in combination with concomitant chemoradiotherapy in patients with locally advanced stage IIIC1r cervical cancer according to the 2018 FIGO classification.

Background: To evaluate the toxicity of prophylactic extended-field radiation therapy (EFRT) combined with volumetric modulated arc therapy (VMAT) in combination with cisplatin chemotherapy for locally advanced stage IIIC1r cervical cancer [2018 International Federation of Gynecology and Obstetrics (FIGO)].

Materials And Methods: Thirty patients with stage IIIC1r cervical cancer were treated with EFRT combined with concurrent cisplatin. Acute toxicities were evaluated according to the common terminology criteria for adverse events (CTCAE v.5). Delayed toxicities were evaluated according to the classification criteria of radiation damage toxicity of the Radiation Therapy Oncology Group (RTOG). The efficacy of the regimens was evaluated using response evaluation criteria in solid tumors (RECIST v1.1). Spearman correlation was used to analyze the correlation between acute gastrointestinal toxicity (nausea) and the small bowel V45. Predictive value analysis was performed using a receiver operating characteristic (ROC) curve.

Results: There were no grade ≥ 3 acute toxicities. The most common acute toxicity observed was nausea (grade 2 in 40%), which was positively correlated with the volume of the small intestine receiving 45 Gy. When the V45 of the small intestine was > 83.2 cc, the risk of grade 2 acute upper digestive tract toxicity (nausea) increased. The major late toxicities had the following distributions: Grade 1 diarrhea, 36.7%; Grade 1 abdominal pain, 13.3%; and Grade 1 radiation cystitis. No grade ≥ 2 late toxicities were observed.

Conclusions: Treatment of locally advanced stage IIIC1r cervical cancer with EFRT combined with VMAT and concurrent cisplatin chemotherapy was well tolerated, and the acute toxicity profile was acceptable. Significant grade 3 acute/delayed toxicities were not observed.