Required distal mesorectal resection margin in partial mesorectal excision: a systematic review on distal mesorectal spread

Abstract

Background The required distal margin in partial mesorectal excision (PME) is controversial. The aim of this systematic review was to determine incidence and distance of distal mesorectal spread (DMS). Methods A systematic search was performed using PubMed, Embase and Google Scholar databases. Articles eligible for inclusion were studies reporting on the presence of distal mesorectal spread in patients with rectal cancer who underwent radical resection. Results Out of 2493 articles, 22 studies with a total of 1921 patients were included, of whom 340 underwent long-course neoadjuvant chemoradiotherapy (CRT). DMS was reported in 207 of 1921 (10.8%) specimens (1.2% in CRT group and 12.8% in non-CRT group), with specified distance of DMS relative to the tumor in 84 (40.6%) of the cases. Mean and median DMS were 20.2 and 20.0 mm, respectively. Distal margins of 40 mm and 30 mm would result in 10% and 32% residual tumor, respectively, which translates into 1% and 4% overall residual cancer risk given 11% incidence of DMS. The maximum reported DMS was 50 mm in 1 of 84 cases. In subgroup analysis, for T3, the mean DMS was 18.8 mm (range 8–40 mm) and 27.2 mm (range 10–40 mm) for T4 rectal cancer. Conclusions DMS occurred in 11% of cases, with a maximum of 50 mm in less than 1% of the DMS cases. For PME, substantial overtreatment is present if a distal margin of 5 cm is routinely utilized. Prospective studies evaluating more limited margins based on high-quality preoperative magnetic resonance imaging and pathological assessment are required.

Prognostic impact of tumor budding in rectal cancer after neoadjuvant therapy: a systematic review and meta-analysis

“…To the best of our knowledge, no study has compared the prognostic roles of the two budding types in patients after neoadjuvant therapy for rectal cancer. Recent studies have shown that patients with rectal cancer undergoing radical surgical resection after long-course nCRT still have a 1.2% likelihood of distal rectal mesenteric cancer cell spread, and distal surgical margins of 40 and 30 mm would result in 10% and 32% residual tumors, respectively [ 35 ]. Furthermore, compared to nCRT, patients with TNT and postoperative adjuvant treatment for rectal cancer receive longer cycles of systemic chemotherapy, and this treatment option is more likely to prevent and remove residual cancer cells and occult metastatic lesions in the area where the patient’s primary cancer is resected, thereby diminishing the likelihood of LR and DM.…”

Impact of Microscopically Positive (≤1 mm) Distal Margins on Disease Recurrence in Rectal Cancer Treated by Neoadjuvant Chemoradiotherapy

“…In other words, a ≤1 mm clear margin width seems to be inadequate in low responders, probably due to the overwhelmingly high risk of residual tumor burden beyond the distal edge of the tumor [ 22 , 23 , 24 ]. Indeed, a distal margin of ≤1 mm in low responders means not only a higher risk of mucosal/submucosal spread of tumor over the resection edge, but also a higher likelihood of incomplete mesorectal excision with possible residual nodal disease [ 25 ], despite similar mean numbers of harvested nodes being observed with close vs. clear margins (14.6 vs. 15.1, p = 0.604). Furthermore, patients treated with nCRT more often had low or ultralow rectal cancer, and coloanal anastomosis was more frequently performed.…”