IMPORTANCE Childhood cancer is a leading cause of mortality among children and adolescents in the developed world and the incidence increases by 0.9% each year. Leukemia accounts for about 30% of all childhood cancer but its etiology is still mostly unknown.OBJECTIVE To conduct a meta-analysis of available scientific evidence on the association between breastfeeding and childhood leukemia.DATA SOURCES A thorough search for articles published between January 1960 and December 2014 researching the association between breastfeeding and childhood leukemia was conducted on PubMed, the Cochrane Library, and Scopus (performed in July and December 2014), supplemented by manual searches of reference lists.STUDY SELECTION To be included in the meta-analyses, studies had to be case control; include breastfeeding as a measured exposure and leukemia as a measured outcome; include data on breastfeeding duration in months; and be published in a peer-reviewed journal with full text available in English. DATA EXTRACTION AND SYNTHESISThe search identified 24 relevant studies, 17 of which met all inclusion criteria. No publication bias or significant heterogeneity among these 17 studies were detected. The quality of each study that met the inclusion criteria was assessed using the Newcastle-Ottawa Scale. Multiple meta-analyses were conducted using the random effect model on raw data in the StatsDirect statistical program. MAIN OUTCOMES AND MEASURESNo or short duration of breastfeeding and the incidence of childhood leukemia. RESULTSThe meta-analysis of all 17 studies indicated that compared with no or shorter breastfeeding, any breastfeeding for 6 months or longer was associated with a 20% lower risk for childhood leukemia (odds ratio, 0.80; 95% CI, 0.72-0.90). A separate meta-analysis of 15 studies indicated that ever breastfed compared with never breastfed was associated with a 9% lower risk for childhood leukemia (odds ratio, 0.91; 95% CI, 0.80-1.04), although the definition of never breastfed differed between studies. All meta-analyses of subgroups of the 17 studies showed similar associations. Based on current meta-analyses results, 14% to 20% of all childhood leukemia cases may be prevented by breastfeeding for 6 months or more.CONCLUSIONS AND RELEVANCE Breastfeeding is a highly accessible, low-cost public health measure. This meta-analysis that included studies not featured in previous meta-analyses on the subject indicates that promoting breastfeeding for 6 months or more may help lower childhood leukemia incidence, in addition to its other health benefits for children and mothers.

Colorectal cancer is a leading cause of morbidity and mortality worldwide in both men and women. The gut microbiome is increasingly recognized as having an important role in human health and disease. Fusobacterium has been identified in former studies as a leading gut bacterium associated with colorectal cancer, but it is still not clear if it plays an oncogenic role. In the current study, fecal samples were collected prior to bowel preparation from participants of screening colonoscopy in the German BliTz study. Using 16S rRNA gene analysis, we examined the presence and relative abundance of Fusobacterium in fecal samples from 500 participants, including 46, 113, 110 and 231 individuals with colorectal cancer, advanced adenomas, non-advanced adenomas and without any neoplasms, respectively. We found that the abundance of Fusobacterium in feces was strongly associated with the presence of colorectal cancer (P-value < 0.0001). This was confirmed by PCR at the species level for Fusobacterium nucleatum. However, no association was seen with the presence of advanced adenomas (P-value = 0.80) or non-advanced adenomas (P-value = 0.80), nor were there any associations observed with dietary or lifestyle habits. Although a causal role cannot be ruled out, our observations, based on fecal microbiome, support the hypothesis that Fusobacterium is a passenger that multiplies in the more favorable conditions caused by the malignant tumor rather than a causal factor in colorectal cancer development.

Colorectal cancer (CRC) is a biologically heterogeneous disease. To characterize its mutational profile, we conduct targeted sequencing of 205 genes for 2,105 CRC cases with survival data. Our data shows several findings in addition to enhancing the existing knowledge of CRC. We identify PRKCI , SPZ1 , MUTYH , MAP2K4 , FETUB , and TGFBR2 as additional genes significantly mutated in CRC. We find that among hypermutated tumors, an increased mutation burden is associated with improved CRC-specific survival (HR = 0.42, 95% CI: 0.21–0.82). Mutations in TP53 are associated with poorer CRC-specific survival, which is most pronounced in cases carrying TP53 mutations with predicted 0% transcriptional activity (HR = 1.53, 95% CI: 1.21–1.94). Furthermore, we observe differences in mutational frequency of several genes and pathways by tumor location, stage, and sex. Overall, this large study provides deep insights into somatic mutations in CRC, and their potential relationships with survival and tumor features.