PS02.080: CLINICAL SIGNIFICANCE OF THE NUMBER OF PERITUMORAL LYMPHATIC VESSELS AFTER CHEMOTHERAPY IN ESOPHAGEAL CANCER PATIENTS
Abstract Background Neoadjuvant chemotherapy (NAC), a standard treatment for locally-advanced esophageal cancer, often achieves significant antitumor effect as clinically or microscopically confirmed. However, how chemotherapy histologically impacts upon normal tissues, in particular lymphatic vessels, adjacent to a tumor remains unclear. Methods A total of 137 patients who underwent curative esophagectomy with (NAC group n = 62)/without (nonNAC group n = 75) NAC for thoracic esophageal cancer in our department from 2004 to 2012 were analyzed. The number of lymphatic vessels (NLV) adjacent to primary tumor (within 1000μm from the edge of tumor) in lamina propria mucosae layer was assessed by immunostaining of D2–40 and its association with clinico-pathological parameters was analyzed. Results The NLV was significantly lower in the NAC group as compared with the nonNAC group (NAC vs nonNAC; 19.1 ± 9.0 vs 22.8 ± 8.6, P = 0.014). In the nonNAC group, when classified into two (high vs low NLV) groups by using the cutoff value of the median NLV in nonNAC group, NLV did not correlated with any clinico-pathological factors including age, gender, tumor location, pT, pN, pM, ly, v, and overall survival. On the other hand, in the NAC group, high NLV (classified by the same cutoff value as noted above) was significantly associated with good histological response (grade1b-2) (high vs low NLV; 52 vs 26%, P = 0.026) and less development of lymph node recurrence (16 vs 40%, P = 0.029) but not with other parameters including age, gender, tumor location, pT, pN, pM, ly, and v. Notably, the high NLV group showed the more favorable 5-year overall survival compared to the low NLV group (61 vs 49%, P = 0.0041). Multivariate analysis of overall survival further identified low NLV (HR = 3.68, 95%CI 1.54–10.83, P = 0.0005) to be one of independent prognostic factors along with pT(HR = 2.87, 95%CI 1.37–6.35, P = 0.0050) and pN(HR = 4.04, 95%CI 1.53–13.89, P = 0.0034) in the NAC group. Conclusion NAC might decrease the number of lymphatic vessels adjacent to primary tumor in resected specimen, and this number was associated with tumor response to NAC and long-term outcome in patients who underwent NAC plus surgery. Disclosure All authors have declared no conflicts of interest.