Abstract
AimThis study aimed to investigate circumferential resection margin (CRM) as a prognostic factor for long‐term oncologic survival after rectal cancer surgery.MethodsPatients diagnosed with malignant rectal cancer between 1 January 2010 and 31 December 2014, from the Surveillance, Epidemiology, and End Results (SEER) program were identified for this study. The patients were divided into five CRM groups to compare the baseline characteristics and assess cancer‐specific survival (CSS): 0‐1 mm, 1.1‐2.0 mm, 2.1‐5.0 mm, 5.1‐10.0 mm, and >10 mm. The main endpoint was CSS.ResultsCircumferential resection margin ≤1 mm was independently associated with 99% increased risk of cancer‐specific mortality in rectal cancer [hazard ratio (HR) = 1.990, 95% confidence interval (CI) = 1.613‐2.454, P < 0.001, using CRM (1.1‐2.0 mm) as a reference]. CRM (5.1‐10.0 mm) was independently associated with 29.2% decreased risk of cancer‐specific mortality [HR = 0.708, 95% CI = 0.525‐0.954, P = 0.152, using group (2.1‐5.0 mm) as reference]. CRM ≤2 mm or ≤0.4 mm was not obviously associated with CSS.Conclusionscircumferential resection margin is an independent prognostic factor in rectal cancer. Surgeons should try to maximize the CRM. Rectal cancer patients with CRM ≤1 mm should receive more postoperative attention depending on individual situation. Also, CRM should be accurately measured in millimeters in a preoperative magnetic resonance imaging or pathological report, rather than simply described as “involved” or “clear.”
Highlights
Circumferential resection margin (CRM) is the closest distance between the radial resection margin and the tumor tissue by eitherQi Liu and Dakui Luo contributed to this work.direct tumor spread, areas of neural or vascular invasion, or the nearest involved lymph node.[1]
While several studies showed that CRM should not be used as a prognostic factor in rectal cancer,[4,5] other studies demonstrated the importance of CRM as an independent prognostic factor of local recurrence and long-term survival,[6,7,8,9] including the first report by Quirke et al[10] suggesting that CRM might be a strong predictor of long-term oncologic outcomes
According to the European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for rectal cancer, CRM is defined as involved if it is ≤1 mm from the tumor-free margin, leading to an increased risk of local recurrence, distant metastases, and poorer survival.[11]
Summary
The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript
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