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Natural killer cells (NK cells) play a major role in the immune response to cancer. An important element of NK target recognition is the binding of human leucocyte antigen (HLA) class I molecules by killer immunoglobulin-like receptors (KIRs). Colorectal carcinoma (CRC) is one of the most common types of inflammation-based cancer. The purpose of the present study was to investigate the presence of KIR genes and HLA class I and II alleles in 1074 CRC patients and 1272 controls. We imputed data from single-nucleotide polymorphism (SNP) Illumina OncoArray to identify associations at HLA (HLA-A, B, C, DPB1, DQA1, DQB1, and DRB1) and KIRs (HIBAG and KIR*IMP, respectively). For association analysis, we used PLINK (v1.9), the PyHLA software, and R version 3.4.0. Only three SNP markers showed suggestive associations ( p < 10 -3 ; rs16896742, rs28367832, and rs9277952). The frequency of KIR2DS3 was significantly increased in the CRC patients compared to healthy controls ( p < 0.005). Our results suggest that the implication of NK cells in CRC may not act through allele combinations in KIR and HLA genes. Much larger studies in ethnically homogeneous populations are needed to rule out the possible role of allelic combinations in KIR and HLA genes in CRC risk.

Objectives: To explore the association of colorectal cancer with environmental solar radiation and sun exposure behavior, considering phenotypic variables (eye color, hair color and skin phenotype), dietary intake of vitamin D and calcium, and socio-demographic factors., Study Design: Multicenter population-based frequency matched case-control study in Spain (MCC-Spain), with 2140 CRC cases and 3950 controls., Methods: Data were obtained through personal interviews using a structured epidemiological questionnaire that included socio-demographic data, residential history, environmental exposures, behavior, phenotypic and dietary information. An environmental-lifetime sun exposure score was constructed combining residential history and average daily solar radiation, direct and diffuse. Logistic regression was used to explore the association between different variables. A structural equation model was used to verify the associations of the conceptual model., Results: We found a lower risk of CRC in subjects frequently exposed to sunlight during the previous summer and skin burning due to sun exposure. No association was observed in relation to the residential solar radiation scores. Subjects with light eye or light hair colors had a lower risk of CRC that those with darker colors. Dietary calcium and vitamin D were also protective factors, but not in the multivariate model. The structural equation model analysis suggested that higher sun exposure was associated with a decreased risk of CRC, as well as dietary intake of calcium and vitamin D, and these factors are correlated among themselves and with environmental solar radiation and skin phenotypes., Conclusion: The results agree with previous observations that sun exposure, dietary vitamin D and calcium intake, and serum 25(OH)D concentration reduce the risk of CRC and indicate that these factors may be relevant for cancer prevention., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: There is an excess incidence of colorectal cancer (CRC) and mortality from this disease in the health area of Leon. The aim of the present study was to determine trends in CRC and its geographical distribution., Methods: Cases included in the Hospital Registry of Tumors of the Centro Asistencial Universitario de León from 1994-2008 and occurring in patients residing in the health area of Leon were studied. Time trends were evaluated with a Poisson regression model. To analyze geographical distribution, the smoothed relative risks (RR) of the municipalities adjusted by the Besag, York and Mollié model were calculated, and their subsequent probability of an RR>1 (PP) was calculated using Bayesian methods., Results: A total of 4,136 cases were included. Rates standardized to the European standard population ranged from 49.6 (1994-6) to 63.5 new cases per 100,000 inhabitants in men (2006-8) and from 29.6 to 33.8 in women. An annual 2% increase was found for all localizations, ranging from 1.8% in the rectum to 3.6% in the proximal colon. In all localizations, the increase was greater in men than in women. Several municipalities in the health area of Leon showed an excess risk. The geographical pattern observed was due especially to the distribution of colon cancer., Conclusions: The incidence rates observed were high and were increasing. Special attention should be paid to CRC in the health area of Leon, mainly in the municipalities with excess risk., (Copyright © 2011 Elsevier España, S.L. and AEEH y AEG. All rights reserved.)