Anastomotic leak and local recurrence in colorectal cancer

We read with interest the systematic review and meta-analysis by Mirnezami et al. The aim of the study is to investigate the long-term oncological influence of anastomotic leak (AL) after restorative surgery for colorectal cancer (CRC) using meta-analysis methods. Principal outcomes evaluated were local recurrence, distant recurrence, and long-term survival. We agree with the authors that the study is subject to a number of limitations. Adjuvant therapy may have a confusing effect on the results of the paper, and also fewer patients with advanced CRC who develop an AL receive adjuvant therapy, when compared with stage-matched groups of patients without an AL. It seems conceivable that failure to receive adjuvant treatment, or delays to the start of therapy due to development of an AL, may facilitate recurrence of CRC. Therefore, we agree with the authors that caution must also be exerted in overinterpretation of the reported findings; a statistical association between AL and increased local recurrence and reduced cancer specific survival does not imply a causative association.