Compared with oncologic surgery of T1 colorectal carcinomas, endoscopic resection had statistically similar outcomes, even in the presence of factors thought to confer increased risk for cancer recurrence, reported Dr. Alexander Meining and his colleagues in the July issue of Clinical Gastroenterology and Hepatology.
The findings suggest that endoscopic resection and surveillance may be a reasonable course, regardless of the histologic character of the tumor involved, considering the mortality rate of the alternative – oncologic colorectal resection – the authors wrote (Clin. Gastroenterol. Hepatol. 2011[doi:10.1016/j.cgh.2011.02.002]).
Dr. Meining, of the department of gastroenterology at the Technischen Universität München in Munich, and his colleagues studied 474 patients who underwent endoscopic resection for T1 colorectal cancers between 1974 and 2002 at Neuperlach Hospital in Munich.
Cancers originating in patients with known inflammatory bowel disease, hereditary cancer syndromes, metachronous advanced colorectal cancers, or known cancers of other origin were excluded.
All the patients had T1 cancers, which are defined by infiltration of the tumor into the submucosal layer. Surgery with oncologic resection was performed in 161 of the patients, and the remaining 313 had their cancers removed by endoscopic means alone, either via snare polypectomy, submucosal saline injection, or – in the case of larger lesions – piecemeal resection.
The decision to perform surgery was based on conventional high-risk characteristics of the tumors, including poorer tumor grading (G3 or G4) or infiltration of lymphatic vessels, as well as individual patients’ preferences and physical ability to withstand surgery.
At the time of resection, tumor grading, resection margins, and determination of venous or lymphatic vessel infiltration were noted, as were polyp characteristics. The depth of submucosal infiltration was not routinely noted, according to the authors.
All patients with complete follow-up data for at least 2 years were then reassessed between January 2003 and September 2004, and the researchers classified each patient as having either good or poor outcomes. Poor outcomes were defined as locoregional cancer relapse, distant metastasis, lymph node metastasis, or death related to advanced colorectal cancer.
Follow-up data were available for 390 patients, or 83% of the original cohort, including 141 surgical patients and 249 patients who were solely treated with the initial endoscopic resection. The mean age of these patients was 63.8 years, 54% were male, and the mean follow-up period was 87 months.
Overall, the authors found that 39 patients (10% of the total) had a poor outcome during either surgery or follow-up, including 17 nonsurgical patients who had endoscopic resection only.
Among these 17 nonsurgical patients, the authors found that lymphatic vessel invasion (stratified as either L0 or L1) carried the highest odds ratio for subsequent poor outcome on follow-up, at 7.8 (P less than .001).
Higher tumor grading (G3/G4 versus G1/G2) also carried a substantial 3.4 odds ratio for poor outcome on follow-up (P = .009). And incomplete resection margins (R0 versus R1/RX) carried an odds ratio of 2.6 (P = .027).
Other presumed risk factors, including tumor configuration (sessile versus pedunculated), localization (right vs. left sided), and venous vessel infiltration (V0 versus V1) did not carry a significant odds ratio for poor outcome during follow-up – a surprising finding, wrote Dr. Meining and his colleagues.
However, while the negative predictive values were high for the risk factors with significant odds ratios (94.6% for lymphatic vessel infiltration, 94.2% for tumor stage, and 96.5% for incomplete endoscopic resection), the corresponding positive predictive values were low: 44.4% for lymphatic vessel infiltration, 42.9% for tumor stage, and 19.6% for incomplete endoscopic resection.
According to Dr. Meining, while the study confirms that lymphatic vessel infiltration is the strongest predictor of metastasis and other poor outcomes, the poor positive predictive values nevertheless confirm not only that "precise assessment of risk remains difficult," but that even in cases of infiltration, surgery may not be warranted."
And regarding the finding that incomplete endoscopic resection also carried an elevated risk, Dr. Meining noted that "endoscopic retreatment of areas suspicious for residual neoplasia should be ... performed if resection was incomplete to the lateral margins."
Nevertheless, Dr. Meining conceded that while "the overwhelming majority of patients can be regarded cured from their cancers in the absence of histological risk factors," surgery may sometimes be the best course for an individual patient, despite the risks.
The researchers wrote that they received no outside funding for this study, and stated that they had no individual interests to disclose.