Peripheral blood immune cell subsets predict postoperative recurrence in colorectal cancer: a flow cytometry-based...

To investigate preoperative peripheral blood immune cell subsets in colorectal cancer (CRC) and their predictive value for postoperative recurrence.

A total of 158 patients with pathologically confirmed stage I-III colorectal cancer who underwent curative-intent surgical treatment were included. Fifty age- and sex-matched healthy volunteers were enrolled as controls for baseline immune cell reference values. Peripheral blood immune cell subsets were assessed preoperatively using flow cytometry. Clinicopathological and laboratory variables, including carcinoembryonic antigen (CEA), neutrophil-to-lymphocyte ratio (NLR), and albumin, were collected. RFS was defined as the time from surgery to postoperative recurrence or last follow-up. Kaplan-Meier analysis and Cox proportional hazards regression were used to evaluate factors associated with postoperative recurrence.

Among the 158 patients with stage I-III CRC, 58 developed recurrence during follow-up. Compared with healthy controls, patients with CRC had lower proportions of CD3⁺ T cells, CD4⁺ T cells, NK cells, and a lower CD4/CD8 ratio, but higher proportions of CD8⁺ T cells, Tregs, and myeloid-derived suppressor cells (MDSCs). Compared with the non-recurrence group, the recurrence group had a higher proportion of stage III disease, higher NLR, lower albumin, and higher levels of Tregs and MDSCs. Kaplan-Meier analysis showed poorer RFS in patients with stage III disease, NLR ≥3.5, high Treg levels, and high MDSC levels. In the combined multivariate Cox model, pathological TNM stage III, NLR ≥3.5, lower albumin, higher Treg levels, and higher MDSC levels were independently associated with postoperative recurrence. The combined model showed an apparent C-index of 0.77 and a bootstrap-corrected C-index of 0.75.

Preoperative immune dysregulation is closely associated with CRC recurrence. A model incorporating immune subsets, inflammatory status, nutritional status, and pathological stage showed favorable discriminatory performance, suggesting that peripheral immune profiling may help refine recurrence risk stratification and personalized follow-up in CRC.