Can CT-PET and Endoscopic Assessment Post-Neoadjuvant Chemoradiotherapy Predict Residual Disease in Esophageal Cancer?

OBJECTIVE: The aim of this study is to assess CT-PET and endoscopic assessment postneoadjuvant chemoradiotherapy (nCRT) in predicting complete pathologic response (pCR) in locally advanced esophageal cancer (LAEC). DESIGN: A prospective cohort study. BACKGROUND: nCRT is increasingly standard of care in LAEC, with pCR a surrogate for excellent outcome. Predicting pCR before surgery, with metabolic imaging and endoscopy, may spare patients' operative intervention. METHODS: One hundred thirty-eight consecutive patients [mean age 61 ± 8, 99 male (72%), 103 (75%) adenocarcinoma] underwent nCRT with CT-PET and endoscopy 4 to 6 weeks later, and surgery subsequently. A complete metabolic response (cMR) was defined as SUVmax of <4. A complete endoscopic response (cER) was no residual mucosal abnormality. The association of pCR with cMR and cER was analyzed. RESULTS: pCR was achieved in 30 patients (22%); 37% SCC and 17% adenocarcinoma. A cMR was evident in 63 (46%), of whom 17 (27%) had a pCR and 17(27%) were ypN+. A cER was observed in 45 (33%). The Spearman correlation for cER and cMR was 0.066 (P = 0.479), for cER and pCR was 0.004 (P = 0.969), and cMR and pCR -0.120 (P = 0.160). The sensitivity, specificity, positive predictive value, and negative predictive value of cMR was 57%, 57%, 27%, and 82%, respectively, and for combined cMR and cER was 24%, 83%, 28%, and 79%, respectively. CONCLUSIONS: The prediction of pCR through CT-PET and endoscopy independently or combined is limited by low sensitivity and poor positive predictive value. Protocols to avoid surgery in patients with apparent complete clinical complete based on these criteria should be adopted with considerable caution.