Detailed Pathological Analysis of the Advancing Edge of the Tumor Can Effectively Stratify Clinical T4b Colorectal Cancer Patients

Abstract

Aims

Pathological staging of colorectal cancers (CRCs) that involve adhesion to adjacent organs (clinical stage T4b, cT4b) is sometimes difficult because the morphology of the invasive front varies. To resolve this issue, we reviewed 492 surgically resected CRC samples, comprising 96 cT4b tumors and, for comparison, 335 typical pathological stage (p) T3 and 61 pT4a tumors.

Methods and results

Cases were subdivided into four groups according to the presence or absence of microscopic tumor invasion into the muscular wall of the adjacent organs and peri‐tumoral abscess along invasive front. Those that directly invaded the wall of the adjacent organs without peri‐tumoral abscess were associated with a significantly worse overall (OS) and recurrence‐free survival (RFS) than the other three types of cT4b tumors. Tumors with peritumoral abscess showed similar prognosis as typical pT3 tumors even when the advancing edge of the tumor invaded the wall of adjacent organs (staged as pT4b). Tumors showing fibrous adhesion without tumor cell invasion into the muscular wall of the adjacent organs showed similar prognosis as typical pT3 tumors and showed better prognosis than pT4a tumors.

Conclusion

In summary, only CRCs with tumor cell invasion into the muscular wall of the adjacent organs should be classified as pT4b, and it might be better to avoid "the presence of tumor cells in fibrous adhesion" to define pathological T4b CRCs. In addition, the presence of a peri‐tumoral abscess should be recorded as a predictor of better prognosis.

This article is protected by copyright. All rights reserved.

http://bit.ly/2AsLuK3