Prognostic value of CD45RO(+) tumor-infiltrating lymphocytes for locally advanced rectal cancer following 30 Gy/10f neoadjuvant radiotherapy

Aim This study aims to evaluate the prognostic value of CD45RO + tumor-infiltrating lymphocytes (TILs) in locally advanced rectal cancer treated with 30 Gy/10 fraction (10f) neoadjuvant radiotherapy. Methods This retrospective study involved 185 patients with locally advanced rectal cancer who underwent 30 Gy/10f nRT (biologic equivalent dose, 30 Gy) followed by total mesorectal excision (TME) between August 2003 and October 2009. The density of CD45RO + TILs was assessed by immunohistochemistry using an image-analysis system and tissue microarray and was evaluated for its association with histopathologic features along with disease-free survival (DFS). Results Following neoadjuvant radiotherapy, the median density of CD45RO + TILs is 654/mm 2 . High density of CD45RO + TILs was significantly associated with increased T and N downstaging effect ( p = 0.006; p = 0.014), lesser-advanced T stage ( p = 0.003) and TNM stage ( p = 0.022). Prolonged DFS (89.0 vs. 68.1 %) was also observed in CD45RO +Hi cases. On multivariate regression model, CD45RO + TILs ( p = 0.026; odds ratio (OR), 0.436 (95 % confidence interval (CI), 0.209–0.907)), tumor differentiation ( p = 0.057; OR, 1.878 (95 % CI, 0.982–3.593)), ypT stage ( p = 0.066; OR, 2.383 (95 % CI, 0.943–6.025)), and ypN stage ( p = 0.009; OR, 2.612 (95 % CI, 1.266–5.388)) were independent factors for DFS. Conclusion The density of CD45RO + TILs cannot only predict tumor downstaging and ypTNM stage for rectal cancer following 30 Gy/10f nRT but also promisingly predict long-term outcomes. These findings may be used to stratify patients and make alternative strategy of adjuvant treatment.