TNM, stage and key biological markers direct the choice of adjuvant chemotherapy. Stage II colon cancer (CC) is a heterogeneous disease with different clinical behavior. For this reason there is a high degree of uncertainty in recommending adjuvant chemotherapy. Pathological features are routinely employed to distinguish high and low risk stage II disease. Adjuvant chemotherapy is usually suggested in the high-risk population. Published data suggest that specific tumor-infiltrating lymphocytes (S-TILs) (CD3 + , CD8 + , CD45RO+) may represent a valuable prognostic tool to drive the decision-making process.
We performed an analysis on 49 cases of CC patients underwent to adjuvant therapy, of which 34 relapsed and 15 did not. We analyzed the density of CD3 + , CD8+ and CD45RO+ (memory cells) in the surgical samples after radical surgery by IHC in the center of the tumor (CT) and in its invasive margin (IM). Measurements were recorded by image analysis as the number of positive cells per tissue surface unit in square millimeters. For each marker, we identified two grading of staining, high density (HD) or low density (LD), where the cut-off was the median value observed. DFS and OS between HD and LD were compared by Log Rank test. This analysis was conducted to stratify patients in two cohorts: stage II (26 pts) and stage III (23 pts).
We limit the present report to the cumulative analysis of each cohort. In CT, HD CD3+ affects OS (p = 0.034) and HD CD45RO+ affects DFS(p = 0.002) in stage II pts. We did not observed any impact in OS nor in DFS for stage III pts. In IM, no correlation was found with OS, both in stage II and III pts, while for DFS HD CD3 + , CD8+ and CD45RO+ showed significant benefit compared to LD (p = 0.016, p = 0.0095 and p = 0.0014 respectively) only in stage II pts.
S-TILs (CD3 + , CD8 + , CD45RO+) might represent a valuable prognostic tool to drive the decision-making process especially for stage II CC disease. All these observations suggest a more pronounced role of S-TILs in IM compared to CT. Our results will be verified in ongoing large prospective study.
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M.C. Merlano: Consultant for Merck Serono. All other authors have declared no conflicts of interest.