We aimed to clarify the oncological significance of the number of lymph nodes in rectal cancers treated with preoperative chemoradiotherapy.We studied 126 curatively operated patients with clinical T3-T4 and M0 rectal cancers. The number of lymph nodes and clinicopathological features were compared between the patients treated with surgery alone (OP group, n = 45) and those treated with preoperative chemoradiotherapy (50-50.4 Gy in 25-28 fractions with tegafur-uracil and leucovorin, CRT group, n = 81). Factors influencing lymph node count and its prognostic significance were analyzed.The CRT group had significantly fewer lymph nodes than the OP group (12.4 vs. 21.1, P0.0001). High histological regression of rectal lesions was significantly correlated with decreased lymph node count in the CRT group. In the OP group, the 5-year cancer-specific survival rate of the patients with 12 or more lymph nodes was significantly better than those with fewer than 12 lymph nodes (75.1% vs. 33.3%, P = 0.02); in the CRT group, on the other hand, these survival rates did not differ (84.5% vs. 77.5%, P = 0.6).The number of lymph nodes in rectal cancer was correlated with the response of primary rectal lesions to chemoradiotherapy, and was not associated with patient survival.
