Extent of lymphadenectomy and prognosis after esophageal cancer surgery

IMPORTANCE The prognostic role of the extent of lymphadenectomy during surgery for esophageal cancer is uncertain and requires clarification. OBJECTIVE To clarify whether the number of removed lymph nodes influences mortality following surgery for esophageal cancer. DESIGN, SETTING, AND PARTICIPANTS Conducted from January 1, 2000, to January 31, 2014, this was a cohort study of patients who underwent esophagectomy for cancer in 2000-2012 at a high-volume hospital for esophageal cancer surgery, with follow-up until 2014. EXPOSURES The main exposure was the number of resected lymph nodes. Secondary exposures were the number of metastatic lymph nodes and positive to negative lymph node ratio. MAIN OUTCOMES AND MEASURES The independent role of the extent of lymphadenectomy in relation to all-cause and disease-specific 5-year mortality was analyzed using Cox proportional hazard regression models, providing hazard ratios (HRs) with 95%CIs. The HRs were adjusted for age, pathological T category, tumor differentiation, margin status, calendar period of surgery, and response to preoperative chemotherapy. RESULTS Among 606 included patients, 506 (83.5%) had adenocarcinoma of the esophagus, 323 (53%) died within 5 years of surgery, and 235 (39%) died of tumor recurrence. The extent of lymphadenectomy was not statistically significantly associated with all-cause or disease-specific mortality, independent of the categorization of lymphadenectomy or stratification for T category, calendar period, or chemotherapy. Patients in the fourth quartile of the number of removed nodes (21-52 nodes) did not demonstrate a statistically significant reduction in all-cause 5-year mortality compared with those in the lowest quartile (0-10 nodes) (HR, 0.86; 95%CI, 0.63-1.17), particularly not in the most recent calendar period (HR, 0.98; 95%CI, 0.57-1.66 for years 2007-2012). A greater number of metastatic nodes and a higher positive to negative node ratio was associated with increased mortality rates, and these associations showed dose-response associations. CONCLUSIONS AND RELEVANCE This study indicated that the extent of lymphadenectomy during surgery for esophageal cancer might not influence 5-year all-cause or disease-specific survival. These results challenge current clinical guidelines.