High dose simultaneous integrated boost for node positive cervical cancer

INTRODUCTION: Lymph node metastases presenting with locally advanced cervical cancer are poor prognostic features. Modern radiotherapy approaches enable dose escalation to radiologically abnormal nodes. This study reports the results of a policy of a simultaneous integrated boost (SIB) in terms of treatment outcomes. MATERIALS AND METHODS: Patients treated with radical chemoradiation with weekly cisplatin for locally advanced cervical cancer including an SIB to radiologically abnormal lymph nodes were analysed. All patients received a dose of 45 Gy in 25 fractions and a SIB dose of 60 Gy in 25 fractions using intensity modulated radiotherapy/volumetric modulated arc therapy, followed by high dose rate brachytherapy of 28 Gy in 4 fractions. A control cohort with radiologically negative lymph nodes was used to compare impact of the SIB in node positive patients. Treatment outcomes were measured by overall survival (OS), post treatment tumour response and toxicities. The tumour response was based on cross sectional imaging at 3 and 12 months and recorded as local recurrence free survival (LRFS), regional recurrence free survival (RRFS) and distant recurrence free survival (DRFS). RESULTS: In between January 2015 and June 2017, a total of 69 patients with a median follow up of 30.9 months (23 SIB patients and 46 control patients) were identified. The complete response rate at 3 months was 100% in the primary tumour and 83% in the nodal volume receiving SIB. The OS, LRFS, RRFS and DRFS at 3 years of the SIB cohort were 69%, 91%, 79% and 77% respectively. High doses can be delivered to regional pelvic lymph nodes using SIB without excessive toxicity. CONCLUSION: Using a SIB, a total dose of 60 Gy in 25 fractions chemoradiation can be delivered to radiologically abnormal pelvic nodes with no increase in toxicity compared to node negative patients. The adverse impact of positive nodal status may be negated by high dose deposition using SIB, but larger prospective studies are required to confirm this observation.