Mesothelin expression has prognostic value in stage ΙΙ/ΙΙΙ colorectal cancer

Mesothelin (MSLN) is a cell-surface glycoprotein present on mesothelial cells and in many cancers, where expression is generally associated with an unfavorable prognosis. The clinical significance and pathological characteristics of MSLN expression were evaluated by immunohistochemical staining of tissues from 530 stage ΙΙ/ΙΙΙ colorectal cancer (CRC) patients with R0 resection. Eighty-eight (16.6%) were MSLN-positive; 33 (37.5%) showed a luminal staining pattern whereas 55 (62.5%) showed a non-luminal staining pattern. MSLN expression, including the luminal and non-luminal staining patterns, was associated with shorter cancer-specific survival (CSS) period in stage ΙΙ (n = 314, P = 0.024) and stage ΙΙΙ (n = 216, P = 0.0002) CRC patients. The non-luminal staining pattern was correlated with poor prognosis in stage ΙΙ (P = 0.0006) and III (P < 0.0001) CRC, but a luminal staining pattern was not significantly correlated with prognosis. Cox's multivariate analysis revealed that a non-luminal staining pattern was associated with CSS independently of other conventional parameters in stage II (P = 0.040, hazard ratio (HR) = 2.92) and III (P = 0.020, HR = 2.13) CRC patients. Immunohistochemical evaluation of MSLN expression was helpful in the prediction of patient prognosis in stage II/III CRC.