Deep submucosal invasion not independently linked to metastasis in colorectal cancer

In the absence of other histological risk factors, deep submucosal invasion (DSI) is not strongly predictive of lymph node metastasis (LNM) in patients with T1 colorectal cancer, reports a recent meta-analysis.

Drawing from the online databases of Medline, Embase, and the Cochrane Library, researchers included 67 studies in the present quantitative synthesis, with a total pooled sample of 21,238 patients. Only studies that controlled for other risk factors in multivariable analyses, and those that described LNM rate of DSI in the absence of such risk factors, were eligible for inclusion.

Pooling data from 66 studies revealed an overall LNM rate of 11.2 percent; the one excluded study did not report LNM. Unadjusted analysis showed that DSI was indeed a risk factor for LNM, increasing such odds by more than twofold (odds ratio [OR], 2.58, 95 percent confidence interval [CI], 2.10–3.18). This was robust to sensitivity analyses.

However, adjusting for other risk factors, such as poor differentiation, lymphovascular invasion, and high-grade tumour budding, attenuated the significant impact of DSI on LNM (OR, 1.73, 95 percent CI, 0.96–3.12). Meanwhile, all three individual risk factors were significantly associated with heightened risks of LNM.

Similarly, when taken as the sole risk factor, DSI was also only weakly associated with LNM, yielding an absolute risk of 2.6 percent.

“These results challenge the early perspective and oncologic dogma of DSI as a strong indicator for oncologic surgery,” the researchers said. “In light of the expanding spectrum of local resection methods and increasing interest in organ preservation, a management shift toward local excision as the initial approach for amenable DSI cases to guide shared decision making is expected.”