Cécile Pizot

Vitamin D status and ill health: a systematic review

Low serum concentrations of 25-hydroxyvitamin D (25[OH]D) have been associated with many non-skeletal disorders. However, whether low 25(OH)D is the cause or result of ill health is not known. We did a systematic search of prospective and intervention studies that assessed the effect of 25(OH)D concentrations on non-skeletal health outcomes in individuals aged 18 years or older. We identified 290 prospective cohort studies (279 on disease occurrence or mortality, and 11 on cancer characteristics or survival), and 172 randomised trials of major health outcomes and of physiological parameters related to disease risk or inflammatory status. Investigators of most prospective studies reported moderate to strong inverse associations between 25(OH)D concentrations and cardiovascular diseases, serum lipid concentrations, inflammation, glucose metabolism disorders, weight gain, infectious diseases, multiple sclerosis, mood disorders, declining cognitive function, impaired physical functioning, and all-cause mortality. High 25(OH)D concentrations were not associated with a lower risk of cancer, except colorectal cancer. Results from intervention studies did not show an effect of vitamin D supplementation on disease occurrence, including colorectal cancer. In 34 intervention studies including 2805 individuals with mean 25(OH)D concentration lower than 50 nmol/L at baseline supplementation with 50 μg per day or more did not show better results. Supplementation in elderly people (mainly women) with 20 μg vitamin D per day seemed to slightly reduce all-cause mortality. The discrepancy between observational and intervention studies suggests that low 25(OH)D is a marker of ill health. Inflammatory processes involved in disease occurrence and clinical course would reduce 25(OH)D, which would explain why low vitamin D status is reported in a wide range of disorders. In elderly people, restoration of vitamin D deficits due to ageing and lifestyle changes induced by ill health could explain why low-dose supplementation leads to slight gains in survival.

Trends in colorectal cancer mortality in Europe: retrospective analysis of the WHO mortality database

Objective To examine changes in colorectal cancer mortality in 34 European countries between 1970 and 2011. Design Retrospective trend analysis. Data source World Health Organization mortality database. Population Deaths from colorectal cancer between 1970 and 2011. Profound changes in screening and treatment efficiency took place after 1988; therefore, particular attention was paid to the evolution of colorectal cancer mortality in the subsequent period. Main outcomes measures Time trends in rates of colorectal cancer mortality, using joinpoint regression analysis. Rates were age adjusted using the standard European population. Results From 1989 to 2011, colorectal cancer mortality increased by a median of 6.0% for men and decreased by a median of 14.7% for women in the 34 European countries. Reductions in colorectal cancer mortality of more than 25% in men and 30% in women occurred in Austria, Switzerland, Germany, the United Kingdom, Belgium, the Czech Republic, Luxembourg, and Ireland. By contrast, mortality rates fell by less than 17% in the Netherlands and Sweden for both sexes. Over the same period, smaller or no declines occurred in most central European countries. Substantial mortality increases occurred in Croatia, the former Yugoslav republic of Macedonia, and Romania for both sexes and in most eastern European countries for men. In countries with decreasing mortality, reductions were more important for women of all ages and men younger than 65 years. In the 27 European Union member states, colorectal cancer mortality fell by 13.0% in men and 27.0% in women, compared with corresponding reductions of 39.8% and 38.8% in the United States. Conclusion Over the past 40 years, there has been considerable disparity in the level of colorectal cancer mortality between European countries, as well as between men and women and age categories. Countries with the largest reductions in colorectal cancer mortality are characterised by better accessibility to screening services, especially endoscopic screening, and specialised care.

Effect of vitamin D supplementation on non-skeletal disorders: a systematic review of meta-analyses and randomised trials

Randomised trials reported up to Dec 31, 2012, did not confirm that vitamin D supplementation could protect from non-skeletal health conditions affecting adults, as was expected on the basis of data from observational studies. To examine whether the more recently published meta-analyses and trials would change past conclusions, we systematically reviewed meta-analyses of vitamin D supplementation and non-skeletal disorders published between Jan 1, 2013, and May 31, 2017, that included study participants of all ages, including pregnant women. We also searched for randomised trials not included in meta-analyses. We identified 87 meta-analyses, of which 52 were excluded because they contained less recent literature or were of suboptimal quality. We retrieved 202 articles on trials that were not included in meta-analyses. Recent meta-analyses reinforce the finding that 10-20 μg per day of vitamin D can reduce all-cause mortality and cancer mortality in middle-aged and older people. Although vitamin D doses were greater than those assessed in the past, we found no new evidence that supplementation could have an effect on most non-skeletal conditions, including cardiovascular disease, adiposity, glucose metabolism, mood disorders, muscular function, tuberculosis, and colorectal adenomas, or on maternal and perinatal conditions. New data on cancer outcomes were scarce. The compilation of results from 83 trials showed that vitamin D supplementation had no significant effect on biomarkers of systemic inflammation. The main new finding highlighted by this systematic review is that vitamin D supplementation might help to prevent common upper respiratory tract infections and asthma exacerbations. There remains little evidence to suggest that vitamin D supplementation has an effect on most conditions, including chronic inflammation, despite use of increased doses of vitamin D, strengthening the hypothesis that low vitamin D status is a consequence of ill health, rather than its cause. We further hypothesise that vitamin D supplementation could exert immunomodulatory effects that strengthen resistance to acute infections, which would reduce the risk of death in debilitated individuals. We identified many meta-analyses of suboptimal quality, which is of concern. Future systematic reviews on vitamin D should be based on data sharing so that data for participants with the same outcomes measured in the same way can be pooled to generate stronger evidence.

Effectiveness of and overdiagnosis from mammography screening in the Netherlands: population based study

Abstract Objective To analyse stage specific incidence of breast cancer in the Netherlands where women have been invited to biennial mammography screening since 1989 (ages 50-69) and 1997 (ages 70-75), and to assess changes in breast cancer mortality and quantified overdiagnosis. Design Population based study. Setting Mammography screening programme, the Netherlands. Participants Dutch women of all ages, 1989 to 2012. Main outcome measures Stage specific age adjusted incidence of breast cancer from 1989 to 2012. The extra numbers of in situ and stage 1 breast tumours associated with screening were estimated by comparing rates in women aged 50-74 with those in age groups not invited to screening. Overdiagnosis was estimated after subtraction of the lead time cancers. Breast cancer mortality reductions during 2010-12 and overdiagnosis during 2009-11 were computed without (scenario 1) and with (scenario 2) a cohort effect on mortality secular trends. Results The incidence of stage 2-4 breast cancers in women aged 50 or more was 168 per 100 000 in 1989 and 166 per 100 000 in 2012. Screening would be associated with a 5% mortality reduction in scenario 1 and with no influence on mortality in scenario 2. In both scenarios, improved treatments would be associated with 28% reductions in mortality. Overdiagnosis has steadily increased over time with the extension of screening to women aged 70-75 and with the introduction of digital mammography. After deduction of clinical lead time cancers, 32% of cancers found in women invited to screening in 2010-12 and 52% of screen detected cancers would be overdiagnosed. Conclusions The Dutch mammography screening programme seems to have little impact on the burden of advanced breast cancers, which suggests a marginal effect on breast cancer mortality. About half of screen detected breast cancers would represent overdiagnosis.

Cancer mortality in cohorts of workers in the European rubber manufacturing industry first employed since 1975

BACKGROUND Increased cancer risk has been reported among workers in the rubber manufacturing industry employed before the 1960s. It is unclear whether risk remains increased among workers hired subsequently. The present study focused on risk of cancer mortality for rubber workers first employed since 1975 in 64 factories. PATIENTS AND METHODS Anonymized data from cohorts of rubber workers employed for at least 1 year from Germany, Italy, Poland, Sweden, and the UK were pooled. Standardized mortality ratios (SMRs), based on country-specific death rates, were reported for bladder and lung cancer (primary outcomes of interest), for other selected cancer sites, and for cancer sites with a minimum of 10 deaths in men or women. Analyses stratified by type of industry, period, and duration of employment were carried out. RESULTS A total of 38 457 individuals (29 768 men; 8689 women) contributed to 949 370 person-years. No increased risk of bladder cancer was observed [SMR = 0.80, 95% confidence interval (CI) 0.46; 1.38]. The risk of lung cancer death was reduced (SMR = 0.81, 95% CI 0.70; 0.94). No statistically significant increased risk was observed for any other cause of death. A reduced risk was evident for total cancer mortality (SMR = 0.81, 95% CI 0.76; 0.87). Risks were lower for workers in the tyre industry compared with workers in the general rubber goods sector. Analysis by employment duration showed a negative trend with SMRs decreasing with increasing duration of employment. In an analysis of secondary end points, when stratified by type of industry and period of first employment, excess risks of myeloma and gastric cancer were observed each due, essentially, to results from one centre. CONCLUSION No consistent increased risk of cancer death was observed among rubber workers first employed since 1975, no overall analysis of the pooled cohort produced significantly increased risk. Continued surveillance of the present cohorts is required to confirm the absence of long-term risk.

Vitamin D status and ill health – Author's reply

Giovannucci enquires whether intervention studies were long enough to allow full expression of health benefits associated with high serum 25-hydroxyvitamin D (25[OH]D) concentrations. Recent meta-analyses that compared top to bottom quantiles of 25(OH)D found summary relative risks of 0·67 (95% CI: 0·59–0·75) in 16 studies of type 2 diabetes1 and of 0·66 (0·54–0·81) in eight studies of colorectal cancer.2 We plotted relative risks of diabetes and colorectal cancer occurrence reported by prospective studies against follow-up duration (figure).

Meaningless METS: studying the link between physical activity and health

Future studies must streamline their measurement and reporting for real gains in knowledge

Stable incidence of advanced breast cancer argues against screening effectiveness

Swedish trials on mammography screening of women aged 40-74 years indicated that two to four rounds of screening could significantly reduce the risk of being diagnosed with and dying from advanced breast cancer.1 Because stage at diagnosis is independent of treatment efficacy, the trials concluded that the introduction of screening in general populations …