Background: Reproducible and well characterized prognostic histomorphologic criteria added to current pathological staging could have an immediate effect on refining prognosis in colorectal cancer. The aim of this study was to determine the additive effect of tumor border configuration and peritumoral lymphocytic infiltration on the selection of patients for adjuvant therapy classified by TNM.
Methods: A total of 1420 primary colorectal cancers with complete clinicopathological data from multiple treatment centers were analyzed. The prognostic effect of tumor border configuration (pushing or infiltrating) and peritumoral lymphocytic infiltration was assessed, validated by resampling of the data, and compared with TNM staging. All P values were 2-sided.
Results: Multivariate analysis confirmed the adverse prognostic value of the tumor border configuration (P < .001), but not of peritumoral lymphocytic infiltration. The addition of tumor border configuration to T and N category identified 2 major prognostic subgroups (relative risk of death, 4.75; 95% confidence interval [CI], 2.53-8.94). Moreover, stage II patients with a pushing border had a 5-year survival rate of 82.1% (95% CI, 71.8%-90.3%), whereas an infiltrating border resulted in a significantly more adverse outcome (5-year survival rate, 62.7%; 95% CI, 48.0-76.2%), closely resembling that of stage III patients. Similar results were obtained after adjusting for adjuvant therapy (P < .001).
Conclusions: The classification of patients into prognostic subgroups is improved with the addition of tumor border configuration to TNM stage. In particular, patients with stage II disease characterized by an infiltrating tumor border have poor clinical outcome and represent a subset of lymph node-negative patients who could be considered for adjuvant therapy.