Variation in circumferential resection margin: Reporting and involvement in the South-Netherlands

Background: Since the introduction of total mesorectal surgery the outcome of rectal cancer patients has improved significantly. Involvement of the circumferential resection margin (CRM) is an important predictor of increased local recurrence, distant metastases and decreased overall survival. Abdomino perineal excision (APE) is associated with increased risk of CRM involvement. Aim of this study was to analyze reporting of CRM and to identify predictive factors for CRM involvement. Methods: A population-based dataset was used selecting 2153 patients diagnosed between 2008 and 2013 with primary rectal cancer undergoing surgery. Variation in CRM reporting was assessed and predictive factors for CRM involvement were calculated and used in multivariate analyses. Results: Large variation in CRM reporting was found between pathology departments, with missing cases varying from 6% to 30%. CRM reporting increased from 77% in 2008 to 90% in 2012 (p <0.001). CRM involvement significantly decreased from 12% to 6% over the years (p <0.001). In multivariate analysis type of operation, low anterior resection or APE, did not influence the risk of CRM involvement. Clinical T4-stage [odds ratio (OR) = 3.51; 95% confidence interval (CI) = 1.85-6.65) was associated with increased risk of CRM involvement, whereas neoadjuvant treatment (5 x 5 gray radiotherapy [OR 0.39; CI 0.25-0.62] or chemoradiation therapy [OR 0.30; CI 0.17-0.53]) were associated with significant decreased risk of CRM involvement. Conclusion: Although significant improvements are made during the last years there still is variation in reporting of CRM involvement in the Southern Netherlands. In multivariate analysis APE was no longer associated with increased risk of CRM involvement.