Intraepithelial CD8+ T-cell-count becomes a prognostic factor after a longer follow-up period in human colorectal carcinoma: possible association with suppression of micrometastasis

Br J Cancer. 2004 Nov 1;91(9):1711-7. doi: 10.1038/sj.bjc.6602201.


T-cell infiltration into human cancer tissues can be a manifestation of host immune responses to cancer cells. The present study was undertaken to explore the clinicopathological significance of intraepithelial CD8(+) T cells using 371 consecutively sampled human colorectal carcinomas. By univariate analysis, we noted that the survival curves by intraepithelial CD8(+) T cells became separated only after 1 to 2 years postoperation. Multivariate analyses revealed that the beneficial effect of this factor becomes significant only after a longer (more than 2 year), but not after a shorter (less than 2 year) follow-up period. Furthermore, the number of intraepithelial CD8(+) T cells was significantly higher in patients alive for more than 5 years than in patients who either died of cancer after a curative operation or patients who underwent a noncurative operation. Patients' cancer-specific death long after a curative operation is thought to be caused by the growth of micrometastases in other organs or near the primary sites. The effects of intraepithelial CD8(+) T cells, therefore, may be mediated by suppression of micrometastasis, rather than suppression of growth in the primary tumour. In conclusion, our data support a hypothesis on the presence of systemic immunosurveillance against micrometastasis of cancer cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • CD8-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes / pathology*
  • Carcinoma in Situ / immunology*
  • Carcinoma in Situ / surgery
  • Colorectal Neoplasms / immunology*
  • Colorectal Neoplasms / surgery
  • Female
  • Follow-Up Studies
  • Humans
  • Lymphatic Metastasis / pathology*
  • Lymphocyte Count
  • Lymphocytes, Tumor-Infiltrating / immunology
  • Lymphocytes, Tumor-Infiltrating / pathology*
  • Male
  • Middle Aged
  • Neoplasm Invasiveness / pathology
  • Prognosis
  • Retrospective Studies
  • Survival Rate