Independent prognostic value of eosinophil and mast cell infiltration in colorectal cancer tissue

Overall peritumoural inflammatory cell infiltration is a prognostic variabl e in solid tumours, but the survival-related impact of the individual cell types within the infiltrate has still not been fully evaluated and compared with the conventional disease classification, In the present study; the pr ognostic value of individual white cell counts in the peritumoural inflamma tory infiltrate in colorectal cancer was assessed. Intra-operative tumour t issue samples from 584 patients undergoing elective surgery for colorectal cancer were included. None of the patients received pre- or post-operative adjuvant chemotherapy, Tissue blocks were cut from the periphery of the tum ours and embedded in paraffin, All blocks included both tumour tissue and n ormal bowel tissue. Serial sections of 4 mu m were analysed for tumour tiss ue inflammatory cell infiltration using a computer- and video-assisted micr oscope, which allowed semi-automated quantification of cells within a fixed area. Total white cells and individual counts of eosinophils, neutrophils, mast cells, lymphocytes, and plasma cells were evaluated in every tumour s pecimen. Stratification into four groups with similar numbers of events was used to dichotomize the cell counts with respect to survival, The median o bservation period was 61 (49-75) months. In a multivariate analysis includi ng Dukes' stage, gender, age, peri-operative blood transfusion, tumour loca tion, and counts of specific inflammatory cells, only advanced Dukes' stage (p<0.0001), high age (p = 0.0003), and tumour location in the rectum predi cted poor survival, while high counts of eosinophils (p = 0.006) and mast c ells (p=0.02) predicted good survival. Tumour-associated eosinophilia and m astocytosis appear to be independent prognostic variables in colorectal can cer. Future studies should investigate the potential biological role of tum our tissue eosinophils and mast cells in the modulation of tumour growth. C opyright (C) 1999 John Wiley & Sons, Ltd.