Effect of lymph node retrieval rates on the utilization of adjuvant chemotherapy in stage II colon cancer

Background: Failing to meet the benchmark of 12 lymph nodes in resection specimens is an indication for adjuvant chemotherapy in stage II colon cancer. Methods: Among consecutive eligible patients with pathologic stage II colon cancer treated at eight NCI-designated comprehensive cancer centers between September 1, 2005 and February 19, 2008, we analyzed receipt of adjuvant chemotherapy, with less than 12 versus 12+ lymph nodes removed and examined the primary explanatory variable of interest. Results: Among 258 patients, 46% received adjuvant chemotherapy. An oxaliplatin-containing regimen was used 67% of the time. Younger age (<50 years, P<0.001), presence of lymphovascular invasion (P=0.007), and higher T stage (P=0.007) were independently associated with adjuvant chemotherapy use. There was significant inter-institutional variability in practice with the proportion receiving treatment ranging from 17% to 64% (P<0.05). Notably, presence of less than 12 lymph nodes in the surgical specimen was a strong predictor of treatment (P=0.008). Conclusions: Adjuvant chemotherapy use after resection of stage II colon cancer is common, but by no means standard practice at National Comprehensive Cancer Network (NCCN) institutions. More attention to achieving the recommended benchmark for lymph node dissection has the potential to decrease exposure to the toxicity of adjuvant treatment.