Dear Editor:

I read the recent publication “Elevated preoperative neutrophil to lymphocyte ratio (NLR) predicts risk of recurrence following curative resection for stage IIA colon cancer (Int J Colorectal Dis. 2010 Sep 7. [Epub ahead of print])” by Ding et al. with great interest. Ding et al. concluded that the NLR was a predictor. I have some additional discussions on the use of NLR. First, the basic problem of the hematological parameters derived from different kinds of automated hematology analyzers has to be raised. The differences in white blood count among the various analyzers from different manufacturers can be expected (Lab Hematol. 2003; 9:175–8; Southeast Asian J Trop Med Public Health. 2002; 33 Suppl 2:62–7). In the retrospective study by Ding et al., it cannot be sure that there might not be any problems due to kinds of analyzers. Second, there are also many other conditions that can lead to the shift of the NLR. The good examples include bacterial and viral infections (Rinsho Byori. 1991; 39:159–66).