Lymph node dissection after chemoradiation in esophageal cancer: a subgroup analysis of patients with and without pathological response.

Background: Extensive lymph node dissection (LND) is beneficial in primarily resected esophageal cancer patients. Such benefit was believed to be seen in neoadjuvant chemoradiotherapy (CRT)-treated patients, but evidence was inconsistent. We hypothesized that CRT might offset the benefit of LND in certain subgroup of patients, especially in major responders.
Methods: The clinical pathological data and survival of esophageal squamous cell carcinoma patients who received curative resection after CRT between 1996 and 2007 were analyzed. On the basis of the mean LND number of the cohort, patients were divided into two groups: group 1, lower LND, and group 2, higher LND.
Results: The cohort comprised 303 patients (295 men and 8 women) with a mean age of 55.4 years. There were 179 patients in group 1 and 124 patients in group 2. One hundred one patients had pathological complete response (pCR). There were more pCR in group 1 (38 vs. 26.6%, P = 0.039) and more lymph node positive cases in group 2 (16 vs. 27.4%, P = 0.018). Extent of LND had no survival difference in the entire cohort (overall survival 32 vs. 38%, P = 0.31). With the stratification analysis according to tumor response, inadequate LND exhibited negative impact in patients who did not experience pCR (P = 0.027). Without adequate LND, the survival of ypTxN0 was equally poor as ypN-positive cases (overall survival 15 vs. 16%, P = 0.791). In the pCR group, the extent of LND had an impact on survival.
Conclusions: The effect of LND was influenced by tumor response after CRT. There is a strong survival benefit for extensive LND after CRT in esophageal squamous cell carcinoma, especially in non-pCR patients.