Impact of age on the prognostic value of number of lymph nodes retrieved in patients with stage II colorectal cancer

A small number of lymph nodes retrieved (NLNR) is a known risk factor in stage II colorectal cancer. NLNR is influenced by age, but little is known about whether the impact of small NLNR on survival differs with age. This retrospective study sought to determine such impact in elderly patients with stage II colorectal cancer. We reviewed data for 2100 patients with stage II colorectal cancer who underwent surgery without adjuvant chemotherapy between January 1997 and December 2003. The optimal cutoff value of NLNR for survival was determined, and the impact of small NLNR on survival was analyzed. The association between age and NLNR was evaluated. The relation between age and risk of small NLNR with respect to survival was then assessed to determine the impact of small NLNR on elderly patients' survival. The optimal cutoff value of NLNR was determined as 6. The small NLNR group (SNG) showed significantly worse prognosis than the large NLNR group (LNG) (p < 0.001). Age, surgical method, and scope of lymph node dissection were significantly associated with NLNR. A potential interaction was noted between age and risk of small NLNR in relation to relapse-free survival (RFS). Five-year RFS was significantly worse in SNG than in LNG for elderly patients (41.7 and 76.4 %, respectively; p < 0.001) but not for non-elderly patients (75.9 and 84.6 %, respectively; p = 0.083). NLNR < 6 was identified to be an important prognostic factor for elderly patients with stage II colorectal cancer.