Clinical factors affecting the distal margin in rectal cancer surgery

In rectal cancer surgery, an insufficient distal margin (DM) is associated with a high risk of local recurrence, whereas an excessive DM will cause low anterior resection syndrome, impairing quality of life. This study aimed to identify the factors that affect the distance between the colorectal resection site and the tumor to optimize achieving the correct DM.

The subjects of this study were 219 patients who underwent resection for primary rectal cancer in our department between January 2006 and July 2014. According to Japanese guidelines, DM (rDM) was based on the tumor location, but the pathological DM (pDM) was measured from surgical specimens. The patients were divided into two groups: the pDM-less-than-rDM group (pDM < rDM) and the pDM-greater-or-equal-to-rDM group (pDM ≥ DM). The factors associated with the DM in the two groups were compared.

In the pDM < rDM group, the tumor distance from the anal verge was shorter (p = 0.001) and significantly more patients underwent laparotomy (p = 0.047).

The DM tended to be shorter than that planned by the surgeon in patients with lower rectal cancers and those treated by laparotomy,; therefore, when performing rectal resection, care must be taken to ensure that the pDM is not shorter than the rDM.