RA07.09: THE EFFICACY OF ASSESSING METASTATIC LYMPH NODES BY COMPUTED TOMOGRAPHY IN ADVANCED ESOPHAGEAL CANCER WITH NEOADJUVANT CHEMOTHERAPY

Abstract

Abstract Background Although various modalities including CT, endoscopy, and positron emission tomography (PET) have been used to predict pathological tumor response (pTR) to neoadjuvant chemotherapy (NACT) or prognosis in esophageal cancer patients, an optimal method of response evaluation remains to be established. Methods A total of 97 non-T4 thoracic esophageal cancer patients who underwent curative surgery after NACT from 2011 to 2014 with both measurable primary tumors (PT) and metastatic lymph nodes (LNs) by CT (≥ 10mm in short axis or ≥ 5mm in short axis with SUV-max ≥ 2.5) were analyzed. Patients with ≥ 50% decrease in size of the PT (two-direction measurement) and ≥ 30% decrease in size of LNs (sum of short diameter based on RECIST criteria) were defined as PT- and LNs-responders, respectively. Results The median reduction rate of PT and LNs were 62.0% (5.5–93.4) and 26.7% (60.9–13.6), respectively. Of 97 patients, 62 (69%) and 45 patients (45%) were classified as PT- and LNs-responders respectively. The concordance rate between CT response of PT and LNs was 66% (P = 0.01). CT response of PT was correlated with pTR (P<0.0001) while CT response of LNs was associated with pT (P = 0.0011), pN(P = 0.0004), and pTR (P < 0.0001). Receiver operating characteristic (ROC) curves demonstrated the highest accuracy (AUC 0.75), sensitivity (88.9%) and specificity (60.9%) at the reduction rate of 53% (P = 0.007) which was approximated to the cutoff value we used. In univariate analysis of recurrence free survival (RFS), pT, pN, pM, CT response of both PT and LNs, and pTR were significantly correlated with RFS. Multivariate analysis further identified CT response of LNs (HR 2.68 P = 0.003) and pTR (HR 2.72 P = 0.022) to be independently associated with RFS. When classified into three groups by histological grade and CT response of LNs [group A (grade2–3/LNs-responders), group B (grade1a-1b/LNs-nonresponders), and group C (others)], 2-year RFS were 83% in the groupA, 59% in groupC and 29% in groupB (P < 0.0001), respectively. Conclusion In locally-advanced esophageal cancer patients with NACT followed by surgery, CT response of PT and LNs significantly correlated with pTR. Especially, CT response of LNs was important to predict prognosis in addition to pTR. Disclosure All authors have declared no conflicts of interest.