Factors associated with risk for colorectal cancer recurrence after endoscopic resection of T1 tumors.

Background & Aims: More information is needed on the long-term outcomes of patients who undergo endoscopic resection of colorectal tumors. We evaluated recurrence of colorectal cancer (CRC) after endoscopic resection or a combination of endoscopic research and surgery for T1 colorectal tumors.

Methods: We conducted a retrospective study of 389 patients with T1 CRC treated by endoscopic resection from January 1989 to December 2008 in Sapporo, Japan. We compared outcomes between patients who underwent subsequent surgery (ER + SURG, n = 205) and those who did not (ER only, n = 184) and statistically adjusted baseline differences between the groups according to the propensity scores.

Results: There was almost no risk of cancer recurrence among patients without indications for surgery recommended by the Japanese Society for Cancer of the Colon and Rectum (these indications include tumors with vertical margins, deep submucosal invasion, lymphatic or venous invasion, poor differentiation, or high-grade budding). Among patients with indications for surgery, the cumulative risks of recurrence (CRRs) were 3.7% in the ER + SURG group and 20.1% in the ER only group (P = .001). However, the patients with only deep submucosal invasion had a low CRR, even without surgery (2.3% in the ER + SURG group and 3.4% in the ER only groups, P = .867). In contrast, patients with indications for surgery other than deep submucosal invasion (high-risk patients) had much better outcomes when they also underwent surgery (CRRs: 5.8% in the ER + SURG group vs 58.0% in the ER only group, P < .001).

Conclusions: On the basis of a retrospective study of patients who underwent endoscopic resection for T1 CRC, those with tumors with only submucosal invasion are at low risk for cancer recurrence. However, patients with other high-risk tumor features have greater risks for cancer recurrence and benefit from subsequent surgery.