(ChemotherapyAdvisor) – Patients with high-risk submucosal rectal cancer are at higher risk of recurrence following endoscopic resection than are patients with colon cancer; high-risk rectal tumors should be treated with surgical resection and lymph node dissection, according to the authors of an analysis of data from the largest retrospective multicenter cohort study of outcomes published to date. The findings were published in the journal Gastroenterology.

“Of patients treated with only endoscopic resection, the risk for local recurrence was significantly higher in high-risk patients with submucosal rectal cancers than patients with submucosal colon cancer,” noted Hiroaki Ikematsu, MD, of the National Cancer Center Hospital East, in Kashiwa Japan, and coauthors.

“The addition of surgery is therefore recommended for patients with submucosal rectal cancer with pathology features indicating high risk of tumor progression,” they concluded.

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The team’s retrospective analysis of long-term outcomes among patients with submucosal and rectal cancer who underwent endoscopic or surgical resection included data for 549 patients with colon cancer and 209 with rectal cancer. The median follow-up period was 60.5 months.

Among high-risk patients who underwent endoscopic resection, recurrence rates among colon and rectal cancers were 1.4% and 16.2%, respectively (P<0.01). The 5-year disease-free survival (DFS) rates were 96.5% among patients with colon cancer, and 77.7% among patients with rectal cancer (P<0.01); 5-year overall survival (OS) rates were 98.3% and 96.2%, respectively.

In contrast, patients with high-risk rectal tumors who underwent surgical resection and lymph node resection experienced a much lower recurrence rate;colon cancer  and rectal cancer recurrence rates were 1.9%  and 4.5% (P<0.09), respectively. The 5-year DFS rates among patients undergoing surgery and lymph node dissection for high-risk colon and rectal tumors were 97.3% and 95.0%; OS rates for these patients were 99.1% and 97.3%.

The “location of the tumor was the only significant contributor (hazard ratio 6.73, 95% CI 1.04-43.43; P=0.045)” to DFS in high risk patients who underwent endoscopic resection only, the authors noted. 

The risk of local recurrence “was significantly higher in high-risk submucosal rectal cancer patients treated only by endoscopic resection as compared to similar submucosal colon cancer patients,” the authors concluded.