Early Metabolic Change after Induction Chemotherapy Predicts Histologic Response and Prognosis in Patients with Esophageal Cancer: Secondary Analysis of a Randomized Trial.

ABSTRACT

BACKGROUND: Early metabolic response after preoperative induction chemotherapy (IC) appears to predict histologic response and prognosis in esophageal cancer (EC), but the usefulness of this approach needs further development. OBJECTIVE: We evaluated metabolic response after one cycle of IC using positron emission tomography (PET) to correlate PET response and outcomes. PATIENTS AND METHODS: We retrospectively analyzed PET data from a randomized phase 2 trial (NCT00525915) of chemoradiation and surgery with or without IC for the treatment of EC. PET was performed at baseline, after one cycle of IC, and 5-7 weeks after chemoradiation. The relationship between PET response (≥35% reduction in standardized uptake value [SUV]) after IC and treatment response was analyzed. RESULTS: In 63 patients who received IC, the mean initial SUVmax prior to treatment was 11.9 ± 8.04 and mean SUVmax after one cycle of IC was 6.47 ± 4.45. The mean SUV reduction after IC was 39.3%. Eleven of 37 PET responders achieved a pathologic complete response (pCR), but only two of 22 PET non-responders did (univariate logistic regression; odds ratio 4.25, 95% confidence interval 0.83-21.77; p = 0.08). PET responders to IC had significantly longer overall survival (OS) than PET nonresponders (log-rank p = 0.009). PET response after chemoradiation was not correlated with OS (log-rank p = 0.15). CONCLUSION: Early PET response after IC is prognostic, but subsequent PET changes (for example, after chemoradiation) are not prognostic. Early PET response might have the potential of predicting pCR.