Summary Background By contrast with many observational studies, women in the Women's Health Initiative (WHI) trial who were randomly allocated to receive oestrogen alone had a lower incidence of ...invasive breast cancer than did those who received placebo. We aimed to assess the influence of oestrogen use on longer term breast cancer incidence and mortality in extended follow-up of this cohort. Methods Between 1993 and 1998, the WHI enrolled 10 739 postmenopausal women from 40 US clinical centres into a randomised, double-masked, placebo-controlled trial. Women aged 50–79 years who had undergone hysterectomy and had expected 3-year survival and mammography clearance were randomly allocated by a computerised, permuted block algorithm, stratified by age group and centre, to receive oral conjugated equine oestrogen (0·625 mg per day; n=5310) or matched placebo (n=5429). The trial intervention was terminated early on Feb 29, 2004, because of an adverse effect on stroke. Follow-up continued until planned termination (March 31, 2005). Consent was sought for extended surveillance from the 9786 living participants in active follow-up, of whom 7645 agreed. Using data from this extended follow-up (to Aug 14, 2009), we assessed long-term effects of oestrogen use on invasive breast cancer incidence, tumour characteristics, and mortality. We used Cox regression models to estimate hazard ratios (HRs) in the intention-to-treat population. This study is registered with ClinicalTrials.gov , number NCT00000611. Findings After a median follow-up of 11·8 years (IQR 9·1–12·9), the use of oestrogen for a median of 5·9 years (2·5–7·3) was associated with lower incidence of invasive breast cancer (151 cases, 0·27% per year) compared with placebo (199 cases, 0·35% per year; HR 0·77, 95% CI 0·62–0·95; p=0·02) with no difference (p=0·76) between intervention phase (0·79, 0·61–1·02) and post-intervention phase effects (0·75, 0·51–1·09). In subgroup analyses, we noted breast cancer risk reduction with oestrogen use was concentrated in women without benign breast disease (p=0·01) or a family history of breast cancer (p=0·02). In the oestrogen group, fewer women died from breast cancer (six deaths, 0·009% per year) compared with controls (16 deaths, 0·024% per year; HR 0·37, 95% CI 0·13–0·91; p=0·03). Fewer women in the oestrogen group died from any cause after a breast cancer diagnosis (30 deaths, 0·046% per year) than did controls (50 deaths, 0·076%; HR 0·62, 95% CI 0·39–0·97; p=0·04). Interpretation Our findings provide reassurance for women with hysterectomy seeking relief of climacteric symptoms in terms of the effects of oestrogen use for about 5 years on breast cancer incidence and mortality. However, our data do not support use of oestrogen for breast cancer risk reduction because any noted benefit probably does not apply to populations at increased risk of such cancer. Funding US National Heart, Lung, and Blood Institute; Wyeth.
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The effectiveness of low-fat diets for long-term weight loss has been debated for decades, with many randomised controlled trials (RCTs) and recent reviews giving mixed results. We aimed to summarise ...the large body of evidence from RCTs to determine whether low-fat diets contribute to greater weight loss than participants' usual diet, low-carbohydrate diets, and other higher-fat dietary interventions.
We did a systematic review and random effects meta-analysis of RCTs comparing the long-term effect (≥1 year) of low-fat and higher-fat dietary interventions on weight loss by searching MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Cochrane Database of Systematic Reviews to identify eligible trials published from database inception up until July 31, 2014. We excluded trials if one intervention group included a non-dietary weight loss component but the other did not, and trials of dietary supplements or meal replacement drink interventions. Data including the main outcome measure of mean difference in weight change between interventions, and whether interventions were intended to lead to weight loss, weight maintenance, or neither, were extracted from published reports. We estimated the pooled weighted mean difference (WMD) with a DerSimonian and Laird random effects method.
3517 citations were identified by the search and 53 studies met our inclusion criteria, including 68 128 participants (69 comparisons). In weight loss trials, low-carbohydrate interventions led to significantly greater weight loss than did low-fat interventions (18 comparisons; WMD 1·15 kg 95% CI 0·52 to 1·79; I(2)=10%). Low-fat interventions did not lead to differences in weight change compared with other higher-fat weight loss interventions (19 comparisons; WMD 0·36 kg -0·66 to 1·37; I(2)=82%), and led to a greater weight decrease only when compared with a usual diet (eight comparisons; -5·41 kg -7·29 to -3·54; I(2)=68%). Similarly, results of non-weight-loss trials and weight maintenance trials, for which no low-carbohydrate comparisons were made, showed that low-fat versus higher-fat interventions have a similar effect on weight loss, and that low-fat interventions led to greater weight loss only when compared with usual diet. In weight loss trials, higher-fat weight loss interventions led to significantly greater weight loss than low-fat interventions when groups differed by more than 5% of calories obtained from fat at follow-up (18 comparisons; WMD 1·04 kg 95% CI 0·06 to 2·03; I(2)=78%), and when the difference in serum triglycerides between the two interventions at follow-up was at least 0·06 mmol/L (17 comparisons; 1·38 kg 0·50 to 2·25; I(2)=62%).
These findings suggest that the long-term effect of low-fat diet intervention on bodyweight depends on the intensity of the intervention in the comparison group. When compared with dietary interventions of similar intensity, evidence from RCTs does not support low-fat diets over other dietary interventions for long-term weight loss.
National Institutes of Health and American Diabetes Association.
Summary Background In the post-intervention period of the Women's Health Initiative (WHI) trial, women assigned to treatment with oestrogen plus progestin had a higher risk of cancer than did those ...assigned to placebo. Results also suggested that the combined hormone therapy might increase mortality from lung cancer. To assess whether such an association exists, we undertook a post-hoc analysis of lung cancers diagnosed in the trial over the entire follow-up period. Methods The WHI study was a randomised, double-blind, placebo-controlled trial undertaken in 40 centres in the USA. 16 608 postmenopausal women aged 50–79 years with an intact uterus were randomly assigned by a computerised, stratified, permuted block algorithm to receive a once-daily tablet of 0·625 mg conjugated equine oestrogen plus 2·5 mg medroxyprogesterone acetate (n=8506) or matching placebo (n=8102). We assessed incidence and mortality rates for all lung cancer, small-cell lung cancer, and non-small-cell lung cancer by use of data from treatment and post-intervention follow-up periods. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov , number NCT00000611. Findings After a mean of 5·6 years (SD 1·3) of treatment and 2·4 years (0·4) of additional follow-up, 109 women in the combined hormone therapy group had been diagnosed with lung cancer compared with 85 in the placebo group (incidence per year 0·16% vs 0·13%; hazard ratio HR 1·23, 95% CI 0·92–1·63, p=0·16). 96 women assigned to combined therapy had non-small-cell lung cancer compared with 72 assigned to placebo (0·14% vs 0·11%; HR 1·28, 0·94–1·73, p=0·12). More women died from lung cancer in the combined hormone therapy group than in the placebo group (73 vs 40 deaths; 0·11% vs 0·06%; HR 1·71, 1·16–2·52, p=0·01), mainly as a result of a higher number of deaths from non-small-cell lung cancer in the combined therapy group (62 vs 31 deaths; 0·09% vs 0·05%; HR 1·87, 1·22–2·88, p=0·004). Incidence and mortality rates of small-cell lung cancer were similar between groups. Interpretation Although treatment with oestrogen plus progestin in postmenopausal women did not increase incidence of lung cancer, it increased the number of deaths from lung cancer, in particular deaths from non-small-cell lung cancer. These findings should be incorporated into risk–benefit discussions with women considering combined hormone therapy, especially those with a high risk of lung cancer. Funding National Heart, Lung and Blood Institute, National Institutes of Health.
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Summary Background Some countries fortify flour with folic acid to prevent neural tube defects but others do not, partly because of concerns about possible cancer risks. We aimed to assess any ...effects on site-specific cancer rates in the randomised trials of folic acid supplementation, at doses higher than those from fortification. Methods In these meta-analyses, we sought all trials completed before 2011 that compared folic acid versus placebo, had scheduled treatment duration at least 1 year, included at least 500 participants, and recorded data on cancer incidence. We obtained individual participant datasets that included 49 621 participants in all 13 such trials (ten trials of folic acid for prevention of cardiovascular disease n=46 969 and three trials in patients with colorectal adenoma n=2652). All these trials were evenly randomised. The main outcome was incident cancer (ignoring non-melanoma skin cancer) during the scheduled treatment period (among participants who were still free of cancer). We compared those allocated folic acid with those allocated placebo, and used log-rank analyses to calculate the cancer incidence rate ratio (RR). Findings During a weighted average scheduled treatment duration of 5·2 years, allocation to folic acid quadrupled plasma concentrations of folic acid (57·3 nmol/L for the folic acid groups vs 13·5 nmol/L for the placebo groups), but had no significant effect on overall cancer incidence (1904 cancers in the folic acid groups vs 1809 cancers in the placebo groups, RR 1·06, 95% CI 0·99–1·13, p=0·10). There was no trend towards greater effect with longer treatment. There was no significant heterogeneity between the results of the 13 individual trials (p=0·23), or between the two overall results in the cadiovascular prevention trials and the adenoma trials (p=0·13). Moreover, there was no significant effect of folic acid supplementation on the incidence of cancer of the large intestine, prostate, lung, breast, or any other specific site. Interpretation Folic acid supplementation does not substantially increase or decrease incidence of site-specific cancer during the first 5 years of treatment. Fortification of flour and other cereal products involves doses of folic acid that are, on average, an order of magnitude smaller than the doses used in these trials. Funding British Heart Foundation, Medical Research Council, Cancer Research UK, Food Standards Agency.
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