Predictors of Radiation Field Failure After Definitive Chemoradiation in Patients With Locally Advanced Cervical Cancer.

ABSTRACT

PURPOSE: We identified the predictive factors for locoregional failure after definitive chemoradiation in patients with locally advanced cervical cancer. METHODS: Altogether, 397 patients with locally advanced cervical cancer (stage IB2-IVA) were treated with definitive chemoradiation between June 2001 and February 2010. Platinum-based concurrent chemotherapy was given to all patients with median radiation dose of external beam radiotherapy 50.4 Gy in 28 fractions and intracavitary radiotherapy 30 Gy in 6 fractions. Competing risk regression analysis was used to reveal the predictive factors for locoregional failure. RESULTS: During the median follow-up of 7.2 years, locoregional failure occurred in 51 (12.9%) patients. The estimated 3-year rate of locoregional control was 89%, whereas the overall survival rate was 82%. After univariate and multivariate analyses, large tumor size (>5 cm), young age (≤40 years), nonsquamous histology, positive lymph node on magnetic resonance imaging, and advanced stage (III-IV) were identified as risk factors for locoregional failure (P = 0.003, P = 0.075, P = 0.005, P = 0.055, and P < 0.001, respectively). After risk grouping according to the coefficients from the multivariate model, we identified a high-risk group for locoregional failure after treatment with definitive chemoradiation as follows (1) tumor size larger than 5 cm, and at least 1 other risk factor or (2) tumor size 5 cm or less, and at least 3 other risk factors. The cumulated estimated 3-year rate of locoregional failure of the high-risk group was 26%, which was significantly higher than that of the low-risk group (7%, P < 0.001). The 3-year overall survival rates of the 2 groups were also significantly different (57% vs 86%, P < 0.001). CONCLUSIONS: Large tumor size (>5 cm), young age (≤40 years), nonsquamous histology, positive lymph node on magnetic resonance imaging, and advanced stage are all risk factors for locoregional failure after definitive platinum-based chemoradiation in patients with locally advanced cervical cancer. In the high-risk group, further clinical trials are warranted to improve the locoregional control rate.