Detailed pathological analysis of the advancing edge of the tumour can effectively stratify clinical T4b colorectal cancer patients

摘要

Abstract Aims Pathological staging of colorectal cancers ( CRC s) that involve adhesion to adjacent organs (clinical stages T4b, cT 4b) is sometimes difficult because the morphology of the invasive front varies. To resolve this issue, we reviewed 492 surgically resected CRC samples, comprising 96 cT 4b tumours and, for comparison, 335 typical pathological stages (p) T3 and 61 pT 4a tumours. Methods and results Cases were subdivided into four groups according to the presence or absence of microscopic tumour invasion into the muscular wall of the adjacent organs and peritumoral abscess along invasive front. Those that directly invaded the wall of the adjacent organs without peritumoral abscess were associated with a significantly worse overall ( OS ) and recurrence‐free survival ( RFS ) than the other three types of cT 4b tumours. Those with peritumoral abscess showed similar prognosis to typical pT 3 tumours, even when the advancing edge of the tumour invaded the wall of adjacent organs (staged as pT 4b). Tumours showing fibrous adhesions without tumour cell invasion into the muscular wall of the adjacent organs showed a similar prognosis to typical pT 3 tumours and showed a better prognosis than pT 4a tumours. Conclusion Only CRC s with tumour cell invasion into the muscular wall of the adjacent organs should be classified as pT 4b, and it might be better to avoid ‘the presence of tumour cells in fibrous adhesion' to define pathological T4b CRC s. In addition, the presence of a peritumoral abscess should be recorded as a predictor of better prognosis.