Is the 1-cm Rule of Distal Bowel Resection Margin in Rectal Cancer Based on Clinical Evidence? A Systematic Review

Abstract

BackgroundDistal intramural spread is present within 1 cm from visible tumor in a substantial proportion of patients. Therefore, ≥1 cm of distal bowel clearance is recommended as minimally acceptable. However, clinical results are contradictory in answering the question of whether this rule is valid. The aim of this review was to evaluate whether in patients undergoing anterior resection, a distal bowel gross margin of <1 cm jeopardizes oncologic safety.MethodsA systematic review of the literature identified 17 studies showing results in relation to margins of approximately <1 cm (948 patients) versus >1 cm (4626 patients); five studies in relation to a margin of ≤5 mm (173 patients) versus >5 mm (1277 patients), and five studies showing results in a margin of ≤2 mm (73 patients). In most studies, pre- or postoperative radiation was provided.ResultsA multifactorial process was identified resulting in selection of favorable tumors for anterior resection with the short bowel margin and unfavorable tumors for abdominoperineal resection or for anterior resection with the long margin. In total, the local recurrence rate was 1.0% higher in the <1-cm margin group compared to the >1-cm margin group (95% confidence interval [CI] −0.6 to 2.7; P = 0.175). The corresponding figures for ≤5 mm cutoff point were 1.7% (95% CI −1.9 to 5.3; P = 0.375). The pooled local recurrence rate in patients having ≤2 mm margin was 2.7% (95% CI 0 to 6.4).ConclusionsIn the selected group of patients, <1 cm margin did not jeopardize oncologic safety.

Intersphincteric resection for very low rectal cancer: A review of the updated literature

“…Also, CRT influenced down‐staging of the tumor, and allowed sphincter‐saving operation for some patients who may have required APR 6. In addition to those aspects, shorter distal resection margin proposed by clinicopathological studies has encouraged surgeons to preserve the anus 7, 8, 9, 10, 11, 12, 13. In 1994, Schiessel et al .…”

Role of intraoperative frozen section for assessing distal resection margin after anterior resection

“…Systematic review studies have identified a selection bias in most studies that patients subjected based on surgical decision to AR with short margin are favourable tumours than patients undergoing APR which are usually unfavourable tumours [28]. The other limitations of our study are no correction factor for bowel shrinkage was used, measurement of the extent of distal intramural spread was not performed and there was no simultaneous IOFS assessment of circumferential resection margin.…”

Flattened Tumor Requires a More Careful Attention for Residual Distal Cancer Spread in Locally Advanced Lower Rectal Carcinoma after Chemoradiotherapy

“…The results of our study demonstrated that patients with flattened-type tumors required a DRM of more than 20 mm from the ulcer edge in order to achieve complete cancer clearance, even when tumors had shown a favorable response to pre-CRT. On the contrary, patients with raised-type tumors required a DRM of more than 5 mm from the macroscopic tumor border, and as some researchers previously noted [15], DRM lengths <10 mm might be oncologically acceptable in some cases.…”

“…The standard distal resection margin (DRM) for LRC cases not administered pre-CRT is now set at approximately 1-2 cm [3] as a result of accumulated evidence [11,12,13,14,15], but in contrast, limited knowledge is available on adequate DRMs for LRC after pre-CRT [16,17,18]. After pre-CRT, probably since tumors frequently exhibit reduced extent of cancer and flattening of the surrounding elevated lesion [19,20], a consensus has still not been reached with regard to determination of adequate DRM, especially when the tumor has macroscopically flattened out.…”