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.
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.
Chiba
T
T
Division of Advanced Surgical Science and Technology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Ohtani
H
H
Mizoi
T
T
Naito
Y
Y
Sato
E
E
Nagura
H
H
Ohuchi
A
A
Ohuchi
K
K
Shiiba
K
K
Kurokawa
Y
Y
Satomi
S
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology*; D002278:Carcinoma in Situ / Q000276:immunology* / Q000601:surgery; D015179:Colorectal Neoplasms / Q000276:immunology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008207:Lymphatic Metastasis / Q000473:pathology*; D018655:Lymphocyte Count; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate