Evaluating outcomes and toxicities for a newly implemented MRI-based brachytherapy program for cervical cancer

Abstract

ObjectiveWe report an updated analysis of the outcomes and toxicities of MRI-based brachytherapy for locally advanced cervical cancer from a U.S. academic center. MethodsA retrospective review was performed on patients treated with MRI-based brachytherapy for cervical cancer. EBRT was standardly 45 Gy in 25 fractions with weekly cisplatin. MRI was performed with the brachytherapy applicator in situ. Dose specification was most commonly 7 Gy for 4 fractions with optimization aim of D90 HR-CTV EQD2 of 85–95 Gyα/β=10 Gy in 2 implants each delivering 2 fractions. ResultsNinety-eight patients were included with median follow up of 24.5 months (IQR 11.9–39.8). Stage IIIA-IVB accounted for 31.6% of cases. Dosimetry results include median GTV D98 of 101.0 Gy (IQR 93.3–118.8) and HR-CTV D90 of 89 Gy (IQR 86.1–90.6). Median D2cc bladder, rectum, sigmoid, and bowel doses were 82.1 Gy (IQR 75.9–88.0), 65.9 Gy (IQR 59.6–71.2), 65.1 Gy (IQR 57.7–69.6), and 55 Gy (IQR 48.9–60.9). Chronic grade 3+ toxicities were seen in the bladder (8.2%), rectosigmoid (4.1%), and vagina (1.0%). Three-year LC, PFS, and OS were estimated to be 84%, 61.7%, and 76.1%, respectively. ConclusionMRI-based brachytherapy demonstrates excellent local control and acceptable rates of high-grade morbidity. These results are possible in our population with relatively large volume primary tumors and extensive local disease.