Prospective study of circulating T-lymphocyte subpopulations and disease progression in colorectal cancer

It has recently been reported that CD4+ T-lymphocytes are reduced in advanced colorectal cancer patients. However, it is not clear whether such changes in T-lymphocyte subsets are an early or late event in such patients. The aim of this study was to examine the relationship between these subsets and disease progression in colorectal cancer.

Flow cytometric analysis of T-lymphocyte subsets was performed in 39 patients who, approximately 12 months previously, had undergone surgery for colorectal cancer. These patients were grouped according to whether they developed a recurrence in the following two years. A group of healthy subjects was studied as controls.

There was a significant increase in the median neutrophil count (4.3 vs. 3.7 10(6)/ml) and the median numbers of platelets (282 vs. 216 10(6)/ml) of the recurrence group compared with the control group, respectively (P < 0.05). The median numbers (0.28 vs. 0.73 10(6)/ml) and percentage (29 vs. 38 percent) of CD4+ T-lymphocytes of the recurrence group were significantly reduced compared with that of the control group (P < 0.05). There were also reductions in the median percentage of CD3+ cells (67 vs. 74 percent) and the median numbers of CD4+ T-lymphocytes (0.28 vs. 0.46 10(6)/ml) of the recurrence group compared with the no recurrence group (P < 0.05).

Reduction of CD4+ T-lymphocytes occurs before detectable recurrence of colorectal cancer. Results of the present study are consistent with impaired immunity, as measured by such lymphocyte subset populations, being important in tumor recurrence in colorectal cancer.