MRI-guided adaptive brachytherapy for locally advanced cervix cancer: Treatment outcomes from a single institution in Hong Kong.

BACKGROUND: Paradigm has shifted from 2D to image-guided adaptive brachytherapy (IGABT) for locally advanced cervix cancer (LACC). Increasing reports from pioneering institutions and large retrospective multicenter series have demonstrated improvements in outcome and reduction in toxicity with IGABT. However, there is scarcity of data on magnetic resonance (MR)-IGABT in Chinese patients.

PURPOSE: To evaluate the clinical outcome of MR-IGABT for LACC in a single institution in Hong Kong.

MATERIAL AND METHODS: Patients with FIGO stage IB-IVA LACC treated with definitive external beam radiotherapy +/- concurrent cisplatin followed by MR-IGABT from January 2015 to January 2018 were included. Brachytherapy planning and dose reporting followed the GEC-ESTRO recommendations. Dosimetric and clinical outcomes including local control (LC), pelvic control (PC), cancer-specific survival, overall survival (OS), and toxicity were analyzed.

RESULTS: Forty-two consecutive patients were included. 71% were FIGO stage IIB or above; 52% had pelvic node involvement. Median high-risk clinical target volume (HRCTV) was 34.7 cm3 (12.3-155.1 cm3 ). Median dose to HRCTV D90 was 88.5 Gy (63.4-113.4 Gy) (EQD210 ). Median doses to the D2cc of bladder, rectum, sigmoid, and small bowel were 83.1 Gy, 67.5 Gy, 69.0 Gy, and 68.9 Gy (EQD23 ), respectively. Median followup was 20.3 months (4.0-35.1 months). 24-month actuarial LC, PC, cancer-specific survival, and OS were 90%, 84%, 90%, and 90%, respectively. Stratification by clinical variables showed that FIGO stage had significant impact on LC and dose to HRCTV on both LC and PC. Treatment was well tolerated without any severe late toxicity.

CONCLUSIONS: Intermediate-term results from systematic MR-IGABT for LACC demonstrate very promising outcomes with minimal toxicity. This fills the gap in evidence for MR-IGABT in Chinese patients.