Impact of suboptimal tandem implantation on local control and complications in intracavitary brachytherapy for cervix cancer.

PURPOSE: Correct tandem implantation for cervix cancer intracavitary brachytherapy may be challenging. We investigated whether suboptimal implantation can be related to patient and disease characteristics and may result in subsequent underutilization of brachytherapy in cervical cancer. METHODS AND MATERIALS: Consecutive cervix cancer patients referred for intracavitary brachytherapy after external beam radiation therapy performed in several general hospitals from 2013 to 2017 were included. RESULTS: In 172 patients having 301 procedures, 95 implantations were suboptimal (15% inadequate tandem insertions, 10% subserosal insertion, and 6% uterine perforation on postimplant CT scan). Risk factors were age, myometrium invasion, and uterine retroversion. Median followup was 21 months. Three-year local control and survival rates were 72% and 85%, respectively. Forty-seven patients (27%) failed to receive brachytherapy. Failure to perform brachytherapy was associated with poorer local control (OR = 0.34 [0.17-0.67], p = 0.001). By contrast, suboptimal implantation did not increase local failure or toxicity rates in patients undergoing brachytherapy. No peritoneal carcinomatosis occurred after uterine perforation in our cohort. CONCLUSIONS: Suboptimal implantation was frequent. In the absence of image guidance during implantation, conversion to other treatment modalities (including external beam radiation therapy) due to insertion difficulties resulted in worse local control. With optimization, however, suboptimal brachytherapy implantation did not result in suboptimal dose coverage or poorer local control. Failure to perform a brachytherapy boost correlates with increased local failure risk in patients with cervix cancer, whereas tandem malposition does not. Real-time intraoperative ultrasound guidance may be useful to reduce uterine perforation rates and thus increase brachytherapy use.