Late side effects of 3T MRI-guided 3D high-dose rate brachytherapy of cervical cancer. Institutional experiences

This article reports experiences with 3T magnetic resonance imaging(MRI)-guided brachytherapy (BT) for cervical cancer focusing on late side effects. Between June 2012 and March 2017 a total of 257 uterovaginal BT administrations were performed in 61 consecutive patients with inoperable cervical cancer. All patients were treated with BT combined with external beam radiotherapy. The mean HR-CTV (high risk-clinical target volume) D90 was 87 ± 5.1 Gy equivalent dose corresponding to the conventional fractionation using 2 Gy per fraction (EQD2, range 70.7–97.9 Gy). The mean doses in OAR (organs at risk), namely rectum, sigmoid and bladder were D2 cm${}^3$${}_{rectum}$ = 62.6 ± 6.9 Gy EQD2 (range 38.2–77.2 Gy), D2 cm${}^3$${}_{sigmoid}$ = 66.2 ± 6.8 Gy EQD2 (43.2–78.6 Gy) and D2 cm${}^3$${}_{bladder}$ = 75.1 ± 8.3 Gy EQD2 (58.2–92.6 Gy). There were no signs of late gastrointestinal (GI) toxicity in 49 patients, grade 3 toxicity was seen in 2 patients and grade 4 toxicity in 3 patients. There were no signs of late genitourinary (GU) toxicity in 41 patients, grade 3 toxicity was seen in 4 patients and no signs of grade 4 toxicity were seen. After the treatment, 60 patients (98.4%) achieved locoregional remission. In 54 patients (88.5%) the remission was complete, whereas in 6 patients (9.8%) remission was partial. The use of 3T MRI-guided BT leads to achievement of high rates of local control with limited late morbidity as demonstrated in this series of patients.