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  • Time dependent BTL was only

    2018-10-30

    Time-dependent BTL was only associated with prostate cancer. However, our analyses stratified by timing of BTL measurement relative to cancer diagnosis found associations between both all incident cancers and prostate cancer, and longer BTL measured ≤4years pre-diagnosis. This suggests (as above) that BTL attrition acts as a tumor suppressive process that must be overcome early in carcinogenesis. Interestingly, one longitudinal study of telomere length and cancer development (albeit a cancerous complication of lymphoma treatment) found a similar temporal pattern, with increasing BTL in cases before and immediately (100days) after treatment, followed by accelerated telomere attrition in cancer cases compared to controls (Chakraborty et al., 2009). The complexity of the relationship between BTL attrition and cancer incidence found here is also similar to that reported in our previous study of BTL and air pollution, where short-term pollution exposure increased BTL but long-term exposure decreased it (Hou et al., 2012b). This underscores the complex “give and take” at the niclosamide of telomere regulation, and reiterates the importance of timing BTL collection relative to diagnosis (and potentially exposure and treatment). The following is the supplementary data related to this article.
    Author Contributions
    Introduction Screening the general adult population for colorectal cancer (CRC) and precancerous colorectal adenoma (CRA) can detect curable disease and reduce mortality. However, all the screening methods in current use have substantial limitations (Kuipers et al., 2013; Lieberman, 2014). Screening by colonoscopy or detection of fecal occult blood greatly reduces long-term CRC mortality (Zauber et al., 2012), but at least half of CRC mortality in the U.S.A. can be attributed to avoidance of screening (Meester et al., 2015). Colonoscopy, the primary modality used in the U.S.A., is costly and invasive, and its efficacy depends on the endoscopist\'s skill and the patient\'s bowel preparation. Computed tomographic colonography has different challenges, and the requirement to pursue detected lesions with colonoscopy limits its use for primary screening (Kuipers et al., 2013). Detecting occult blood in feces, particularly with the fecal immunochemical test (FIT) for human hemoglobin, has reasonable acceptability, cost, and accuracy for detecting CRC (single-test sensitivity, 60%–85%; specificity, >90%) (Lieberman, 2014). Improving the predictive value of a positive FIT (FIT+) with molecular analyses of feces or serum is a high priority (Ahlquist et al., 2012; Carmona et al., 2013; Goedert et al., 2014b; Imperiale et al., 2014; Kuipers et al., 2013; Lieberman, 2014), especially because the sensitivity of FIT for CRA is less than 50% and because many FIT+ patients decline follow-up colonoscopy (Lieberman, 2014). Research on differences or alterations in the distal gut microbiota has focused on the pathogenesis of CRC (Collins et al., 2011; Schwabe and Jobin, 2013; Sears and Pardoll, 2011; Tjalsma et al., 2012), and such differences may ultimately prove to be helpful for screening. Comprehensive comparisons of the fecal microbiota have been reported by four studies, totaling 176 CRC cases and 241 controls (Ahn et al., 2013; Wang et al., 2012; Weir et al., 2013; Wu et al., 2013; Zeller et al., 2014). Four of these studies reported that butyrate-producing bacteria were significantly less abundant in feces from CRC cases compared to controls, although the particular taxa varied. In addition, the three larger studies reported that CRC cases had significantly higher carriage or abundance of potentially pathogenic Fusobacteria and Proteobacteria (Ahn et al., 2013; Wang et al., 2012; Zeller et al., 2014). Similar or different bacteria may contribute to the CRA stage of neoplasia (Tjalsma et al., 2012), and data to address this hypothesis are starting to emerge. Abundance of several bacterial taxa was reported to differ in rectal mucosa of CRA cases compared to healthy controls (McCoy et al., 2013; Mira-Pascual et al., 2014; Sanapareddy et al., 2012; Shen et al., 2010), including two studies in which well characterized cases\' unaffected mucosa had higher levels of Proteobacteria taxa than did the controls\' mucosa (Mira-Pascual et al., 2014; Shen et al., 2010).