Importance of positron emission tomography for assessing the response of primary and metastatic lesions to induction treatments in T4 esophageal cancer

Abstract

There is no consensus strategy for treatment of T4 esophageal cancer, and because of this, a better evaluation of treatment response is crucial to establish personalized therapies. This study aimed to establish a useful system for evaluating treatment response in T4 esophageal cancer. This study included 130 patients with cT4 esophageal cancer without distant metastasis who underwent 18F-fluorodeoxyglucose-positron emission tomography before and after a series of induction treatments comprising chemoradiation or chemotherapy. We evaluated the maximal standardized uptake value and treatment response. The mean±standard deviation of standardized uptake value in the primary tumor before and after induction treatments were 13.8±4.4 and 5.4±4.1, respectively, and the mean standardized uptake value decrease was 58.4%. The most significant difference in survival between positron emission tomography-primary tumor responders and nonresponders was at a decrease of 60% standardized uptake value, based on every 10% stepwise cutoff analysis (2-year cause-specific survival: 60.2 vs 23.5%; hazard ratio=2.705; P<.0001). With this cutoff value, the resectability (P=.0307), pathologic response (P=.0004), and pT stage (P<.0001) were associated with positron emission tomography-primary tumor response. Univariate analysis of 2-year cause-specific survival indicated a correlation between cause-specific survival and clinical stages according to TNMclassification, esophageal perforation, positron emission tomography-primary tumor response, lymph node status evaluated by positron emission tomography before and after induction treatments, and operative resection. Multivariate analysis further identified positron emission tomography-primary tumor response (hazard ratio=2.354; P=.0107), lymph node status evaluated by positron emission tomography after induction treatments (hazard ratio=1.966; P=.0089), and operative resection (hazard ratio=2.012; P=.0245) as independent prognostic predictors. Positron emission tomography evaluation of the response of primary and metastatic lesions to induction treatments is important to formulate treatment strategies for cT4 esophageal cancer.