Pushing the envelope beyond a centimeter in rectal cancer: oncologic implications of close, but negative margins

The treatment of rectal cancer has improved significantly over the last century. Advances in surgical and adjuvant therapy coupled with a better understanding of the natural history have allowed for acceptance of progressively diminished margins for distal neoplasms. In order to better define oncologically safe distal margins, we performed a meta-analysis of the existing world's literature.

Studies were identified on Medline and ISI Web of Science using key words rectal cancer and margin. Studies were excluded if specific margins and local recurrence rates could not be extracted. All analyses were performed using Comprehensive Meta-Analysis Software (Biostat).

Twenty-one studies reported outcomes in relationship to distal margins. Seventeen studies, 4,885 patients, reported outcomes with margins of less than 1 cm. Analysis of all studies indicated a nonsignificant trend favoring greater margins. However, in order to understand distal margins in the context of current care standards, additional analyses were performed. Thirteen studies reported application of total mesorectal excision and/or radiation. There was no significant difference in local recurrence rates for margins less than 1 cm. In the 4 studies that reported neither total mesorectal excision nor radiation, a margin greater than 1 cm was favored. Increased recurrence rates and decreased survival were associated with positive final margins.

When total mesorectal excision is combined with radiotherapy, excellent local control can be expected with sphincter preservation for distal rectal cancers when margins are less than 1 cm, as long as final pathologic margins are negative.