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

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.