Positive Radial Margin Warning for Colon Cancer Patients

Positive radial margins are rare in colon cancer but have significant prognostic consequences

medwireNews: Research published in JAMA Surgery highlights the perioperative and survival significance of a positive radial margin in patients undergoing colon cancer surgery.

A positive radial margin, where primary disease is present at the cut edge of the mesentery or nonserosalised portions of the colon, is known to be a negative prognostic indicator in rectal cancer patients but has not been well defined in colon cancer.

“Generally, it is rare that a colon cancer should have a positive radial margin (unlike rectal cancer, in which the resection margins are limited by bony structures) because most structures adjacent to the colon are resectable”, explains Jonathan Efron, from Johns Hopkins University in Baltimore, Maryland, USA, in an invited commentary.

Indeed, the review of 984 patients who underwent surgery for colon cancer between 2004 and 2011 revealed that just 5.3% of patients had a positive radial margin.

But these patients were 3.16 times more likely to require multivisceral resection (40.4 vs 12.8%) and 3.78 times more likely to require conversion from laparoscopic to open surgery (50.0 vs 13.7%) than patients with a negative margin.

All patients with a positive margin had at least stage II disease and were more likely than those without to have positive lymph nodes (86.5 vs 38.8%), metastasis (34.6 vs 6.7%), high-grade disease (45.1 vs 18.2%) and extramural vascular invasion (76.9 vs 28.4%).

And among patients with no evidence of metastasis at baseline, a positive margin was associated with a significant 3.32-fold higher rate of metastasis during follow-up (37.5 vs 12.5%). The likelihood of peritoneal and liver metastasis was particularly elevated, with relative risks of 7.24 and 3.10, respectively.

Overall, 86.4% of patients with a positive margin died during follow-up compared with 32.4% of those with a negative margin, with colon cancer-specific deaths reported for 65.4% and 15.9%, respectively.

After adjusting for age, smoking habits, comorbidity, baseline stage and receipt of neoadjuvant chemotherapy, the hazard ratio for death was 3.39 in patients with a positive versus negative margin.

In the light of these data, Jonathan Efron emphasises: “The same diligence that is currently advocated for rectal cancer is now required for the workup and evaluation of colon cancer.”

Study authors David Berger and co-workers, from Massachusetts General Hospital in Boston, USA, agree: “Indications of radial margin involvement in preoperative imaging should weigh heavily in the planned operative approach as well as any decision regarding adjuvant therapy and may justify the development of specific standardized treatment approaches.”

References

Amri R, Bordeianou LG, Sylla P, Berger DL. Association of radial margin positivity with colon cancer. JAMA Surg 2015; Advance online publication 1 July. doi:10.1001/jamasurg.2015.1525

Efron J. The role of the radial margin. Further call for standardization of colon cancer care. JAMA Surg 2015; Advance online publication 1 July. doi:10.1001/jamasurg.2015.1549

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