Tumour infiltrating lymphocytes as a predictive and prognostic biomarker in rectal cancers treated with neoadjuvant chemoradiotherapy

![CDATA[Current literature documents conflicting results on the prognostic significance of tumour infiltrating lymphocytes (TIL) and the peritumoural lymphocytic reaction as a marker for recurrence and overall survival in patients with curative treatment-naive colorectal cancer. This may be related to the focus on phenotypic rather than functional characterisation of these lymphocytes. Several studies in rectal cancer have shown that lymphocyte density in pre-treatment biopsy samples correlate with treatment response while others have highlighted the contrasting relationship between different T helper subset expressions and prognosis. Peritumoural inflammation was not a significant prognostic factor for 5-year disease-free or overall survival in one rectal cancer cohort1, however preclinical studies have demonstrated the tumour controlling effect of inflammation induced by radiation. This study aims to examine the: (1) TIL subsets in rectal cancers before and after neoadjuvant chemoradiotherapy; (2) relationship between TIL and early tumour response as assessed histologically by the extent of tumour regression; (3) relationship between TIL and late tumour response as measured clinically by the 3-year disease-free survival (DFS).]]