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Fulltext The potential for chemical mixtures from the environment to enable the cancer hallmark of sustained proliferative signalling

Engström W, Darbre P, Eriksson S, Gulliver L, Hultman T, Karamouzis MV, et al.

Carcinogenesis, 2015 Jun;36 Suppl 1:S38-60.
PMID: 26106143 DOI: 10.1093/carcin/bgv030

The aim of this work is to review current knowledge relating the established cancer hallmark, sustained cell proliferation to the existence of chemicals present as low dose mixtures in the environment. Normal cell proliferation is under tight control, i.e. cells respond to a signal to proliferate, and although most cells continue to proliferate into adult life, the multiplication ceases once the stimulatory signal disappears or if the cells are exposed to growth inhibitory signals. Under such circumstances, normal cells remain quiescent until they are stimulated to resume further proliferation. In contrast, tumour cells are unable to halt proliferation, either when subjected to growth inhibitory signals or in the absence of growth stimulatory signals. Environmental chemicals with carcinogenic potential may cause sustained cell proliferation by interfering with some cell proliferation control mechanisms committing cells to an indefinite proliferative span.
Self-rated health and all-cause and cause-specific mortality of older adults: Individual data meta-analysis of prospective cohort studies in the CHANCES Consortium

Bamia C, Orfanos P, Juerges H, Schöttker B, Brenner H, Lorbeer R, et al.

Maturitas, 2017 Sep;103:37-44.
PMID: 28778331 DOI: 10.1016/j.maturitas.2017.06.023

OBJECTIVES: To evaluate, among the elderly, the association of self-rated health (SRH) with mortality, and to identify determinants of self-rating health as "at-least-good".
STUDY DESIGN: Individual data on SRH and important covariates were obtained for 424,791 European and United States residents, ≥60 years at recruitment (1982-2008), in eight prospective studies in the Consortium on Health and Ageing: Network of Cohorts in Europe and the United States (CHANCES). In each study, adjusted mortality ratios (hazard ratios, HRs) in relation to SRH were calculated and subsequently combined with random-effect meta-analyses.
MAIN OUTCOME MEASURES: All-cause, cardiovascular and cancer mortality.
RESULTS: Within the median 12.5 years of follow-up, 93,014 (22%) deaths occurred. SRH "fair" or "poor" vs. "at-least-good" was associated with increased mortality: HRs 1.46 (95% CI 1·23-1.74) and 2.31 (1.79-2.99), respectively. These associations were evident: for cardiovascular and, to a lesser extent, cancer mortality, and within-study, within-subgroup analyses. Accounting for lifestyle, sociodemographic, somatometric factors and, subsequently, for medical history explained only a modest amount of the unadjusted associations. Factors favourably associated with SRH were: sex (males), age (younger-old), education (high), marital status (married/cohabiting), physical activity (active), body mass index (non-obese), alcohol consumption (low to moderate) and previous morbidity (absence).
CONCLUSION: SRH provides a quick and simple tool for assessing health and identifying groups of elders at risk of early mortality that may be useful also in clinical settings. Modifying determinants of favourably rating health, e.g. by increasing physical activity and/or by eliminating obesity, may be important for older adults to "feel healthy" and "be healthy".
Smoking and All-cause Mortality in Older Adults: Results From the CHANCES Consortium

Müezzinler A, Mons U, Gellert C, Schöttker B, Jansen E, Kee F, et al.

Am J Prev Med, 2015 Nov;49(5):e53-e63.
PMID: 26188685 DOI: 10.1016/j.amepre.2015.04.004

INTRODUCTION: Smoking is known to be a major cause of death among middle-aged adults, but evidence on its impact and the benefits of smoking cessation among older adults has remained limited. Therefore, we aimed to estimate the influence of smoking and smoking cessation on all-cause mortality in people aged ≥60 years.
METHODS: Relative mortality and mortality rate advancement periods (RAPs) were estimated by Cox proportional hazards models for the population-based prospective cohort studies from Europe and the U.S. (CHANCES [Consortium on Health and Ageing: Network of Cohorts in Europe and the U.S.]), and subsequently pooled by individual participant meta-analysis. Statistical analyses were performed from June 2013 to March 2014.
RESULTS: A total of 489,056 participants aged ≥60 years at baseline from 22 population-based cohort studies were included. Overall, 99,298 deaths were recorded. Current smokers had 2-fold and former smokers had 1.3-fold increased mortality compared with never smokers. These increases in mortality translated to RAPs of 6.4 (95% CI=4.8, 7.9) and 2.4 (95% CI=1.5, 3.4) years, respectively. A clear positive dose-response relationship was observed between number of currently smoked cigarettes and mortality. For former smokers, excess mortality and RAPs decreased with time since cessation, with RAPs of 3.9 (95% CI=3.0, 4.7), 2.7 (95% CI=1.8, 3.6), and 0.7 (95% CI=0.2, 1.1) for those who had quit <10, 10 to 19, and ≥20 years ago, respectively.
CONCLUSIONS: Smoking remains as a strong risk factor for premature mortality in older individuals and cessation remains beneficial even at advanced ages. Efforts to support smoking abstinence at all ages should be a public health priority.
Fulltext Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead

Goodson WH, Lowe L, Carpenter DO, Gilbertson M, Manaf Ali A, Lopez de Cerain Salsamendi A, et al.

Carcinogenesis, 2015 Jun;36 Suppl 1:S254-96.
PMID: 26106142 DOI: 10.1093/carcin/bgv039

Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety 'Mode of Action' framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology.