Could cancer invasion into blood vessels help predict colon cancer outcomes better than conventional staging alone?

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The researchers evaluated how vascular invasion (VI) compared with nodal (N) stage in predicting colon cancer outcomes, and developed a new staging system that included VI.

The study compared patients with stage II–III colon cancer who had undergone curative resection. Patients were assigned to VI and non-VI groups; the non-VI group was further divided into N0, N1, and N2 categories. The researchers added a V-stage to conventional TNM staging to create TNVM staging.

Among the 2,243 participants, the VI group independently had worse oncological outcomes than the N1 group: the hazard ratio (HR) for disease-free survival (DFS) was 1.704, with a reported range of 1.267–2.291; the HR for overall survival (OS) was 2.301, with a reported range of 1.582–3.348.

Five-year DFS was 63.4% in the VI group, compared with 74.6% in N1b (p = 0.003), 69.7% in N2a (p = 0.126), and 56.8% in N2b (p = 0.276). Five-year OS was 76.6% in the VI group, compared with 84.9% in N1b (p = 0.004), 83.0% in N2a (p = 0.047), and 76.1% in N2b (p = 0.906).

The researchers therefore treated VI as equivalent to N2a in TNVM staging. This moved 78 patients (3.5%) to a higher stage.

With this reclassification, the five-year OS rates for stages IIB and IIC changed from 88.6% and 65.9% under TNM staging to 90.5% and 85.7% under TNVM staging, respectively. These figures describe the survival rates of the reclassified stage groups, not a treatment-related improvement in survival.

The researchers concluded that, in stage II–III colon cancer, VI had a similar prognostic impact to N2 disease without VI. They concluded that incorporating the V-stage into conventional TNM staging enables better prediction of prognosis.