Differences in cytokine levels due to gender in colorectal cancer patients.

Female gender is associated with longer survival after treatment for colorectal cancer (CRC). Reasons behind this phenomenon are not entirely clear. In addition, higher interleukin-6 (IL-6) and interleukin-1 (IL-1) levels have been found to be associated with poorer prognosis in CRC patients. The aim of this study was to investigate if cytokine levels were different in male and female CRC patients. Pre- and post-operative levels of IL-1, interleukin-1 receptor antagonist (IL-1ra), IL-6 and tumour necrosis factor-alpha (TNF-alpha) were measured using standard solid phase sandwich ELISA in 104 consecutive eligible patients undergoing elective resection for CRC. Seventy (67.3%) participants were male and the mean age of the group was 67.6years (standard deviation 10.4years, range 39-86years). Pre-operative IL-1beta and post-operative IL-6 levels were significantly higher in males compared with females (U=486.5, p=0.03, U=424, p=0.04), values approaching statistical significance were obtained for pre-operative IL-6 (U=508.5, p=0.06) and post-operative IL-1beta (U=448, p=0.07). Differences in the levels of TNF-alpha and IL-1ra were not statistically significant. Multiple regression analysis using TNM stage as a covariate, showed that gender was an independent predictor of post-operative IL-6 levels (p=0.04). IL-1beta and IL-6 levels were significantly higher in men than in women. This provides evidence of a possible link between gender and cytokine levels in patients with colorectal cancer.