Local failure after definitive chemoradiation therapy for unresectable esophageal cancer remains problematic. Little is known about the failure pattern based on modern-day radiation treatment volumes. We hypothesized that most local failures would be within the gross tumor volume (GTV), where the bulk of the tumor burden resides.
We reviewed treatment volumes for 239 patients who underwent definitive chemoradiation therapy and compared this information with failure patterns on follow-up positron emission tomography (PET). Failures were categorized as within the GTV, the larger clinical target volume (CTV, which encompasses microscopic disease), or the still larger planning target volume (PTV, which encompasses setup variability) or outside the radiation field.
At a median follow-up time of 52.6 months (95% confidence interval, 46.1-56.7 months), 119 patients (50%) had experienced local failure, 114 (48%) had distant failure, and 74 (31%) had no evidence of failure. Of all local failures, 107 (90%) were within the GTV, 27 (23%) were within the CTV, and 14 (12%) were within in the PTV. On multivariate analysis, GTV failure was associated with tumor status (T3/T4 vs T1/T2; odds ratio, 6.35; P = .002), change in standardized uptake value on PET before and after treatment (decrease >52%: odds ratio, 0.368; P = .003), and tumor size (>8 cm, 4.08; P = .009).
Most local failures after definitive chemoradiation for unresectable esophageal cancer occur in the GTV. Future therapeutic strategies should focus on enhancing local control. Cancer 2011;. © 2011 American Cancer Society.