Circumferential resection margin is a predictor for metastatic disease after rectal cancer surgery: a nation-wide population-based study cohort

Background/Aim To evaluate circumferential resection margin
(CRM) as a risk factor for distant metastasis (DM) in rectal cancer.
The treatment of rectal cancer has evolved over the last decades.
Surgical radicality is the single most important factor in preventing
recurrences, both locally and distantly. CRM B 1.0 mm is considered
to increase recurrence risk. However, not all patients with CRM
B 1.0 mm suffer recurrence. This study explores the risk of DM in
relation to exact CRM. Methods All patients treated with abdominal
resection surgery for rectal cancer between 2005 and 2013 in Sweden
were eligible for inclusion in this retrospective study. Primary endpoint was DM. Results 12,146 cases were identified. 8593 cases were
analysed after exclusion. 718 (8.6%) patients had CRM B 1.0 mm
and 7601 (91.4%) patients CRM [1.0 mm. DM rate was 36.9%
(n = 56/153), 29.2% (n = 165/565), 25.2% (n = 26/103) and 18.5%
(n = 1385/7498) when CRM was 0.0 mm, 0.1–1.0 mm, 1.1–1.9 mm
and CRM C 2 mm respectively. Multivariable analysis revealed
higher DM risk in CRM 0.0 mm versus C 2.0 mm (HR 1.73, 95% c.i.
1.30 to 2.29; P B 0.001) and in CRM 0.1–1.0 mm versus C 2.0 mm
(HR 1.29, 95% c.i. 1.09 to 1.53; P B 0.001). No significant difference
in DM risk in CRM 1.1–1.9 mm versus C 2.0 mm (HR 1.10, 95% c.i.
0.74 to 1.64; P = 0.623) could be detected. Conclusion The risk of
DM decreases with increasing CRM. Moreover, CRM\ 2.0 mm is
an independent, significant risk factor for DM. CRM should be considered when predicting risk of DM after rectal cancer surgery.