In Reply We appreciate the opportunity to respond to the comments provided by the authors of these 2 letters regarding our article.1 The overall message of the letter from Leeds and Fang seems to be that there are important limitations to consider when using the National Cancer Data Base (NCDB) for research and when interpreting the findings from such studies. Regarding the letter from Renehan et al, the main issue seems to be that contemporary European guidelines contraindicate local excision as a management strategy for squamous cell carcinoma of the anal canal (SCCAC), and they too cite additional limitations associated with the use of NCDB data.