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Margins in Rectal Cancer Surgery Methodology

Circumferential/Radial Margin Involvement Rate
Short description of Indicator Percentage of rectal cancer surgery resection reports with involved (positive) circumferential/radial margins​
Rationale for measurement The Ontario Health (Cancer Care Ontario) guideline, “Optimization of Surgical and Pathological Quality Performance in Radical Surgery for Colon and Rectal Cancer: Margins and Lymph Nodes Guideline Recommendations, recommends that negative margins are the goal of rectal resection.

Margin status is a good indicator of the quality of surgery and pathology because it helps predict how the disease will progress, and how likely it is to return (recur). The literature demonstrates decreased local recurrence rates and increased survival in patients with negative margins compared with positive margins for rectal cancer.​
Evidence/references for rationale Recommendations for improving the quality of rectal cancer surgery including margin and lymph assessment can be found in a guideline released in 2016.
Calculations for the indicator % Reports with Positive Margins = (Number of of rectal cancer surgery resection reports with involved (positive) circumferential/radial margins)/(Number of of rectal cancer surgery resection reports)
Standardized Rate Calculation N/A
Unit Percentage (%)
Data sources Pathology Data Mart​
Time Frame CY 2013-2017​
Geographic Scale Provincial
Denominator description Patients that had a rectal cancer resection.

Primary tumour site is one of the following:
  • Rectosigmoid
  • ​Rectum
Numerator description Number of rectal cancer resection reports with positive Radial/Circumferential margins (margins involved by invasive carcinoma)​
Considerations N/A
Data availability & limitations Excludes:
  • All non-cancer cases
  • Reports not received in discrete data field format (i.e., narrative reports)
  • ICD-O-3 behaviors of 0 (benign), 1 (borderline), 6 (metastatic) and 2 (in situ).
  • Consults
  • All report types other than surgical pathology reports; (i.e., biopsies are excluded)
  • Reports from private labs and pediatric hospitals
  • Reports where margin involvement by invasive carcinoma is not identified or margin involement cannot be accessed)
  • Report that contain information on both colon and rectal resection