Objectives To report the impact on survival of residual tumor volume (RTV) prior to brachytherapy (BT) initiation determined by magnetic resonance imaging (MRI) in patients treated for locally advanced cervical cancer with definitive chemoradiotherapy (CRT).

Methods MRI examinations were prospectively performed in patients with advanced cervical cancer (Stages IB2-IVA) after CRT completion and prior to BT initiation. RTV was delineated on each T2-weighted slice and volumetry was derived on the treatment planning system. All patients received external beam radiation (EBRT) with concomitant Cisplatin followed by volume-based BT planning. Cumulative EBRT and BT doses were calculated as the total equivalent dose in 2 Gy fractions (EQD2). Potential prognostic factors were selected based on non-parametric tests and then analyzed for survival with a Cox regression model.

Results Median post-therapy follow-up was 27.4 months (range, 3–57.8). Thirty-seven patients were included. According to the FIGO classification, 8% were stage IB, 75% stage II, 11% stage III, and 6% stage IV. Overall survival was 86.5%. Of the patients evaluated, 29.7% had complete remission on pre-BT MRI and 18.9% were considered having local failure or distant disease. At bivariate analysis, RTV >2 mL, D90 CTV-HR <84 Gy and excessive treatment time were all predictors of poor overall survival. At multivariate regression analysis, only RTV persisted as a significant prognostic factor with survival rates of 95.8% and 69.2% for pre-BT RTV ≤2 mL and >2 mL respectively (p=0.005).

Conclusions Our preliminary data suggest that pre-BT RTV >2 mL is a predictor of poor survival.