Highlights of This Issue

Abstract

Chang et al., Page 23Two studies appearing in this issue evaluate whether cancer risk alleles that were originally identified in populations of European ancestry are also relevant in other patient populations. In one study, He and colleagues examined several colorectal cancer (CRC) risk variants in a multiethnic sample comprised of European American, African American, Native Hawaiian, Japanese American and Latino men and women. He and colleagues confirmed the associations of several CRC/adenoma risk alleles in European Americans and found statistically significant cumulative effects of risk alleles on CRC/adenoma risk in all populations except Japanese Americans. In another study, Chang and colleagues evaluated 27 GWAS-identified loci in prostate cancer patients of African descent. The authors found several significant associations in the African population and these associations were in the same direction and of similar magnitude as those reported in men of European descent. Although several prostate cancer risk alleles were confirmed in men of African descent, not all risk variants were validated. This may be due to different contributions of genetic and non-genetic factors in prostate cancer in men of African or European descent. Both of these studies stress the importance of evaluating the epidemiologic architecture of genetic risk factors in different populations.The medication metformin lowers elevated insulin levels among diabetic patients. Previous studies showed a protective effect of metformin on breast cancer risk. To expand on this work, Bosco and colleagues used Danish medical registries to conduct a nested case-control study evaluating the effect of metformin on breast cancer risk among peri- and postmenopausal type 2 diabetic women. They found that metformin users were indeed less likely to be diagnosed with breast cancer than non-metformin users. These data support the hypothesis that metformin may be a candidate breast cancer prevention agent.Little is known about the relationship between pre- and postmenopausal breast cancer and the combined intake of vitamin D from diet, supplements and sun exposure. To address this, Engel and colleagues evaluated the association between vitamin D intake and mean daily Ultraviolet Radiation dose (UVRd) with the risk of breast cancer among French women. They report that dietary and supplemental vitamin D intakes were not associated with breast cancer risk. Postmenopausal women with high vitamin D intake and living in regions of France with high UVRd, however, had significantly lower breast cancer risk. This study suggests that there may be a Vitamin D threshold exposure for breast cancer prevention.