May’s Paper of the Month is a systematic review and meta-analysis comparing the oncological outcomes, the operative complications and pathological results of two operative techniques for colon cancer; the complete mesocolic excision (CME) versus conventional surgery.

Complete mesocolic excision versus conventional surgery for colon cancer: A systematic review and meta-analysis. Crane J, Hamed M, Borucki JP, El-Hadi A, Shaikh I, Stearns AT. Published: Colorectal Disease 2 May 2021.

The study results demonstrate an overall survival benefit from CME/D3 at 3 and 5 years (relative risk reduction of 31% and 22% respectively) and disease-free survival benefit with relative risk reduction estimated at 40%, 28% and 33% respectively at 1, 3 and 5 years postoperatively.

More lymph nodes were retrieved with CME (6 nodes more than conventional surgery). And while the CME procedure took a longer operative time (28 minutes longer), there was no significant difference in overall complications, anastomotic leak or blood loss when compared with conventional surgery.

Method and outcomes


Systematic review and meta-analysis


Patient with colon cancer who had complete mesocolic excision (D3 dissection) versus patients who had conventional surgery (D1 and D2 dissection)

Primary outcome

Long-term oncological outcomes (overall and disease-free survival) at 1, 3 and 5 years.

Secondary outcomes

  • Perioperative outcomes (operation duration, blood loss, overall complications including anastomotic leakage and 30-day mortality)
  • Pathological outcomes (length of bowel resected, lymph node harvest and risk of R1 resection).


  • 31 studies were included in the review ( out of 2463 screened records)
  • This included 13830 patients in the CME/D3 versus 12810 patients in the conventional cohort.
  • Oncological outcomes:
    • Disease free survival at 1,3, and 5 years was statistically significantly better in CME group with RR 0.60 (95% CI 0.45–0.81, P < 0.001); RR 0.72 (95% CI 0.62–0.83, P = 0.001); RR 0.67 (95% CI 0.52–0.86, P < 0.001) respectively.
    • Overall survival was statistically significantly better in CME group at 3 nd 5 years RR 0.69 (95% CI 0.51–0.93, P = 0.016) and RR 0.78 (95% CI 0.64–0.95, P = 0.011) respectively. And not statistically different at year 1 RR 0.85 (95% CI 0.67–1.09, P = 0.201)
  • Pathological outcomes:
    • LN yield (29 studies): significantly higher in the CME group (weighted mean of 6.1 additional LN)
    • The risk of R1 resection (12 studies): in favour of the CME group: RR 0.61 (95% CI 0.27–1.38, P = 0.234).
    • No difference in the resected bowel length.
  • Perioperative outcomes:
    • No difference in overall complications (21 studies), Anastomotic leak (18 studies), blood loss (31 studies), or 30-day mortality (8 studies)
    • Increased operative time for CME (weighted mean difference 27.7 min, P = 0.041)