Vitamin D supplementation and total cancer incidence and mortality by daily vs. infrequent large-bolus dosing strategies: a meta-analysis of randomised controlled trials.

BACKGROUND: Efficacy of vitamin D supplementation may vary by dosing strategies and adiposity. To address such heterogeneity, we performed a meta-analysis of randomised controlled trials of vitamin D supplementation and total cancer outcomes. METHODS: PubMed and Embase were searched through January 2022. Summary relative risk (SRR) and 95% confidence interval (CI) were estimated using the DerSimonian-Laird random-effects model. RESULTS: For total cancer incidence (12 trials), the SRR for vitamin D supplementation vs. control group was 0.99 (95% CI, 0.94-1.03; P = 0.54; I2 = 0%). No significant association was observed regardless of whether the supplement was given daily or infrequently in a large-bolus. Yet, among trials testing daily supplementation, a significant inverse association was observed among normal-weight individuals (SRR, 0.76; 95% CI, 0.64-0.90; P = 0.001, I2 = 0%), but not among overweight or obese individuals (Pheterogeneity = 0.02). For total cancer mortality (six trials), the SRR was 0.92 (95% CI, 0.82-1.03; P = 0.17; I2 = 33%). A significant inverse association emerged (SRR, 0.87; 95% CI, 0.78-0.96; P = 0.007; I2 = 0%) among studies testing daily supplementations but not among studies that testing infrequent large-bolus supplementations (Pheterogeneity = 0.09). CONCLUSIONS: For vitamin D supplementation, daily dosing, but not infrequent large-bolus dosing, reduced total cancer mortality. For total cancer incidence, bolus dosing did not reduce the risk and the benefits of daily dosing were limited to normal-weight individuals.

The age-dependent association of risk factors with pancreatic cancer.

BACKGROUND: Pancreatic cancer presents as advanced disease in >80% of patients; yet, appropriate ages to consider prevention and early detection strategies are poorly defined. We investigated age-specific associations and attributable risks of pancreatic cancer for established modifiable and non-modifiable risk factors. PATIENTS AND METHODS: We included 167 483 participants from two prospective US cohort studies with 1190 incident cases of pancreatic cancer during >30 years of follow-up; 5107 pancreatic cancer cases and 8845 control participants of European ancestry from a completed multicenter genome-wide association study (GWAS); and 248 893 pancreatic cancer cases documented in the US Surveillance, Epidemiology, and End Results (SEER) Program. Across different age categories, we investigated cigarette smoking, obesity, diabetes, height, and non-O blood group in the prospective cohorts; weighted polygenic risk score of 22 previously identified single nucleotide polymorphisms in the GWAS; and male sex and black race in the SEER Program. RESULTS: In the prospective cohorts, all five risk factors were more strongly associated with pancreatic cancer risk among younger participants, with associations attenuated among those aged >70 years. The hazard ratios comparing participants with three to five risk factors with those with no risk factors were 9.24 [95% confidence interval (CI) 4.11-20.77] among those aged ≤60 years, 3.00 (95% CI 1.85-4.86) among those aged 61-70 years, and 1.46 (95% CI 1.10-1.94) among those aged >70 years (Pheterogeneity = 3×10-5). These factors together were related to 65.6%, 49.7%, and 17.2% of incident pancreatic cancers in these age groups, respectively. In the GWAS and the SEER Program, the associations with the polygenic risk score, male sex, and black race were all stronger among younger individuals (Pheterogeneity ≤0.01). CONCLUSIONS: Established risk factors are more strongly associated with earlier-onset pancreatic cancer, emphasizing the importance of age at initiation for cancer prevention and control programs targeting this highly lethal malignancy.

Prospective evaluation of dietary and lifestyle pattern indices with risk of colorectal cancer in a cohort of younger women.

BACKGROUND: Although colorectal cancer (CRC) incidence in the USA is declining overall, its incidence is increasing among those younger than 50 years of age. The reasons underlying the increasing trend are largely unknown, although behavioral changes, such as unhealthy diet and lifestyle factors, may be partially responsible. DESIGN: A prospective cohort study included 94 217 women aged 26-45 years at baseline. Validated anthropometric measures and lifestyle information were self-reported biennially. Exposures were four recommendation-based dietary indices-the prime diet quality score and three plant-based dietary indices; and two mechanism-based indices-the empirical dietary and lifestyle index for hyperinsulinemia (EDIH and ELIH). We calculated hazard ratios (HRs) and 95% confidence intervals (CIs) for overall CRC and for early-onset (before age 50) and after age 50 CRC separately. RESULTS: We documented 332 cases of CRC during 24 years of follow-up (2 113 655 person-years), with an average age of 52 ± 7 years at diagnosis. Hyperinsulinemic dietary and lifestyle patterns were associated with a higher risk of CRC. Multivariable-adjusted HRs (95% CIs) comparing participants in the highest versus lowest quartile were: 1.67 for EDIH (95% CI: 1.15-2.44, P-trend = 0.01) and 1.51 for ELIH (95% CI: 1.10-2.08, P-trend = 0.01). Moreover, per 75% increment in rank, ELIH appeared to be a stronger risk factor for early-onset CRC (HR = 1.86, 95% CI: 1.12-3.07) than after age 50 CRC (HR = 1.20, 95% CI: 0.83-1.73, P-heterogeneity = 0.16). The four recommendation-based indices were not significantly associated with overall, early-onset, or after age 50 CRC risk (per 75% increment in rank, HRs ranged from 0.75 to 1.28). CONCLUSION: Dietary and lifestyle patterns contributing to hyperinsulinemia were associated with greater CRC risk in younger women. Moreover, the hyperinsulinemic lifestyle showed a suggestively stronger positive association with early-onset CRC risk, compared with after age 50 CRC. Our findings suggest that dietary and lifestyle interventions to reduce insulinemic potential may be effective for CRC prevention among younger women.

Height as a mediator of sex differences in cancer risk.

BACKGROUND: Globally, age-standardized incidence rates for most cancers at shared sites are substantially and consistently higher in men than in women. Differences in established risk factors are unable to account for much of the sex disparity. We hypothesized that variability in height may be important in explaining sex differences in cancer risk. PATIENTS AND METHODS: We included 49 372 men from the Health Professionals Follow-up Study (1986-2014) and 115 612 women from the Nurses' Health Study (1980-2014). Height was reported at baseline and biennial questionnaires were used to collect information on cancer risk factors. We examined the association between sex and cancer incidence at shared anatomic sites using Cox proportional hazards models and performed mediation analysis to determine the percent of the association that was accounted for by height. RESULTS: Over up to 34 years of follow-up, 21 307 incident cases of cancers at shared sites (7705 men, 13 602 women) were documented. After adjusting for major cancer risk factors, men had a 39% increased risk of shared cancers overall (hazard ratio = 1.39; 95% confidence interval = 1.33-1.45) of which 35% (95% confidence interval = 24-46) was mediated by height. The excess risk of cancer for men was also partially explained by height for several specific cancers (gastrointestinal, melanoma, kidney, brain, hematologic). Mediation by height tended to be stronger among never smokers or those who adhered to a healthy lifestyle, and for cancers with fewer known environmental risk factors. CONCLUSIONS: Differences in height among men and women partially mediated the association between sex and cancer incidence at several shared sites. Hence, mechanisms underlying the relationship between height and cancer may be important determinants of sex disparities in cancer incidence.

Measures of body fatness and height in early and mid-to-late adulthood and prostate cancer: risk and mortality in The Pooling Project of Prospective Studies of Diet and Cancer.

BACKGROUND: Advanced prostate cancer etiology is poorly understood. Few studies have examined associations of anthropometric factors (e.g. early adulthood obesity) with advanced prostate cancer risk. PATIENTS AND METHODS: We carried out pooled analyses to examine associations between body fatness, height, and prostate cancer risk. Among 830 772 men, 51 734 incident prostate cancer cases were identified, including 4762 advanced (T4/N1/M1 or prostate cancer deaths) cases, 2915 advanced restricted (same as advanced, but excluding localized cancers that resulted in death) cases, 9489 high-grade cases, and 3027 prostate cancer deaths. Cox proportional hazards models were used to calculate study-specific hazard ratios (HR) and 95% confidence intervals (CI); results were pooled using random effects models. RESULTS: No statistically significant associations were observed for body mass index (BMI) in early adulthood for advanced, advanced restricted, and high-grade prostate cancer, and prostate cancer mortality. Positive associations were shown for BMI at baseline with advanced prostate cancer (HR = 1.30, 95% CI = 0.95-1.78) and prostate cancer mortality (HR = 1.52, 95% CI = 1.12-2.07) comparing BMI ≥35.0 kg/m2 with 21-22.9 kg/m2. When considering early adulthood and baseline BMI together, a 27% higher prostate cancer mortality risk (95% CI = 9% to 49%) was observed for men with BMI <25.0 kg/m2 in early adulthood and BMI ≥30.0 kg/m2 at baseline compared with BMI <25.0 kg/m2 in early adulthood and BMI <30.0 kg/m2 at baseline. Baseline waist circumference, comparing ≥110 cm with <90 cm, and waist-to-hip ratio, comparing ≥1.00 with <0.90, were associated with significant 14%-16% increases in high-grade prostate cancer risk and suggestive or significant 20%-39% increases in prostate cancer mortality risk. Height was associated with suggestive or significant 33%-56% risks of advanced or advanced restricted prostate cancer and prostate cancer mortality, comparing ≥1.90 m with <1.65 m. CONCLUSION: Our findings suggest that height and total and central adiposity in mid-to-later adulthood, but not early adulthood adiposity, are associated with risk of advanced forms of prostate cancer. Thus, maintenance of healthy weight may help prevent advanced prostate cancer.

Meeting report from the joint IARC-NCI international cancer seminar series: a focus on colorectal cancer.

Despite significant progress in our understanding of the etiology, biology and genetics of colorectal cancer, as well as important clinical advances, it remains the third most frequently diagnosed cancer worldwide and is the second leading cause of cancer death. Based on demographic projections, the global burden of colorectal cancer would be expected to rise by 72% from 1.8 million new cases in 2018 to over 3 million in 2040 with substantial increases anticipated in low- and middle-income countries. In this meeting report, we summarize the content of a joint workshop led by the National Cancer Institute and the International Agency for Research on Cancer, which was held to summarize the important achievements that have been made in our understanding of colorectal cancer etiology, genetics, early detection and treatment and to identify key research questions that remain to be addressed.

Vitamin D supplementation and total cancer incidence and mortality: a meta-analysis of randomized controlled trials.

BACKGROUND: Previous meta-analyses of randomized controlled trials (RCTs) of vitamin D supplementation and total cancer incidence and mortality found inconsistent results, and most included trials administered generally low doses of vitamin D (≤1100 IU/day). We updated the meta-analysis by incorporating recent RCTs that have tested higher doses of vitamin D supplements. MATERIALS AND METHODS: PubMed and Embase were searched from the inception to November 2018. Summary relative risks (RRs) and 95% confidence intervals (CIs) were estimated using a random-effects model. RESULTS: For total cancer incidence, 10 trials were included [6537 cases; 3-10 years of follow-up; 54-135 nmol/l of attained levels of circulating 25(OH) vitamin D [25(OH)D] in the intervention group]. The summary RR was 0.98 (95% CI, 0.93-1.03; P = 0.42; I2 = 0%). The results remained null across subgroups tested, including even when attained 25(OH)D levels exceeded 100 nmol/l (RR, 0.95; 95% CI, 0.83-1.09; P = 0.48; I2 = 26%). For total cancer mortality, five trials were included [1591 deaths; 3-10 years of follow-up; 54-135 nmol/l of attained levels of circulating 25(OH)D in the intervention group]. The summary RR was 0.87 (95% CI, 0.79-0.96; P = 0.005; I2 = 0%), which was largely attributable to interventions with daily dosing (as opposed to infrequent bolus dosing). No statistically significant heterogeneity was observed by attained levels of circulating 25(OH)D (Pheterogeneity = 0.83), with RR being 0.88 (95% CI, 0.78-0.98; P = 0.02; I2 = 0%) for ≤100 nmol/l and 0.85 (95% CI, 0.70-1.03; P = 0.11; I2 = 0%) for >100 nmol/l. CONCLUSIONS: In an updated meta-analysis of RCTs, vitamin D supplementation significantly reduced total cancer mortality but did not reduce total cancer incidence.

Plasma Concentrations of Long Chain N-3 Fatty Acids in Early and Mid-Pregnancy and Risk of Early Preterm Birth.

BACKGROUND: Fish oil supplementation has been shown to delay spontaneous delivery, but the levels and clinical significance remain uncertain. We examined the association between plasma fatty acids quantified in pregnancy and subsequent risk of early preterm birth. METHODS: In a case-control design nested in the Danish National Birth Cohort, we identified 376 early preterm cases (<34 gestational weeks, excluding preeclampsia cases) and 348 random controls. Plasma eicosapentaenoic acid plus docosahexaenoic acid (EPA+DHA% of total fatty acids), were measured twice in pregnancy, at gestation weeks 9 and 25 (medians). Odds ratios and 95% confidence intervals (CI's) for associations between EPA+DHA and early preterm risk were estimated by logistic regression, adjusted for the woman's age, height, pre-pregnancy BMI, parity, smoking, and socioeconomic factors. Hypotheses and analytical plan were defined and archived a priori. FINDINGS: Analysis using restricted cubic splines of the mean of 1st and 2nd sample measurements showed a strong and significant non-linear association (p < 0.0001) in which the risk of early preterm birth steeply increased when EPA+DHA concentrations were lower than 2% and flattened out at higher levels. Women in the lowest quintile (EPA+DHA < 1.6%) had 10.27 times (95% confidence interval 6.80-15.79, p < 0.0001) increased risk, and women in the second lowest quintile had 2.86 (95% CI 1.79-4.59, p < 0.0001) times increased risk, when compared to women in the three aggregated highest quintiles (EPA+DHA ≥ 1.8%). INTERPRETATION: Low plasma concentration of EPA and DHA during pregnancy is a strong risk factor for subsequent early preterm birth in Danish women.

Predicted vitamin D status and colon cancer recurrence and mortality in CALGB 89803 (Alliance).

BACKGROUND: Observational studies suggest that higher levels of 25-hydroxyvitamin D3 (25(OH)D) are associated with a reduced risk of colorectal cancer and improved survival of colorectal cancer patients. However, the influence of vitamin D status on cancer recurrence and survival of patients with stage III colon cancer is unknown. PATIENTS AND METHODS: We prospectively examined the influence of post-diagnosis predicted plasma 25(OH)D on outcome among 1016 patients with stage III colon cancer who were enrolled in a National Cancer Institute-sponsored adjuvant therapy trial (CALGB 89803). Predicted 25(OH)D scores were computed using validated regression models. We examined the influence of predicted 25(OH)D scores on cancer recurrence and mortality (disease-free survival; DFS) using Cox proportional hazards. RESULTS: Patients in the highest quintile of predicted 25(OH)D score had an adjusted hazard ratio (HR) for colon cancer recurrence or mortality (DFS) of 0.62 (95% confidence interval [CI], 0.44-0.86), compared with those in the lowest quintile (Ptrend = 0.005). Higher predicted 25(OH)D score was also associated with a significant improvement in recurrence-free survival and overall survival (Ptrend = 0.01 and 0.0004, respectively). The benefit associated with higher predicted 25(OH)D score appeared consistent across predictors of cancer outcome and strata of molecular tumor characteristics, including microsatellite instability and KRAS, BRAF, PIK3CA, and TP53 mutation status. CONCLUSION: Higher predicted 25(OH)D levels after a diagnosis of stage III colon cancer may be associated with decreased recurrence and improved survival. Clinical trials assessing the benefit of vitamin D supplementation in the adjuvant setting are warranted. CLINICALTRIALS.GOV IDENTIFIER: NCT00003835.

Consumption of soy foods and isoflavones and risk of type 2 diabetes: a pooled analysis of three US cohorts.

BACKGROUND/OBJECTIVES: Evidence regarding the consumption of soy foods and isoflavones in relation to risk of type 2 diabetes (T2D) is scarce. Our study was to evaluate the association between soy food and isoflavone consumption and risk of T2D in US men and women. SUBJECTS/METHODS: We followed 63 115 women in the Nurses' Health Study (1998-2012), 79 061 women in the Nurses' Health Study II (1999-2013) and 21 281 men in the Health Professionals Follow-Up Study (2002-2010). Diet was assessed by a validated food-frequency questionnaire and was updated every 4 years. Self-reports of incident T2D were confirmed by a validated supplementary questionnaire. RESULTS: During 1 966 321 person-years of follow-up, 9185 incident T2D cases were documented. After multivariate adjustment for covariates, consumption of soy foods (tofu and soy milk) was not associated with a lower T2D risk. Compared with non-consumers of soy foods, the hazard ratio (HR) was 1.00 (95% confidence interval (CI): 0.93, 1.07) for <1 serving/week and 0.93 (95% CI: 0.83, 1.03) for ⩾1 serving/week of soy foods (P for trend=0.14). In contrast, intake of total isoflavones was inversely associated with T2D risk. Comparing extreme quintiles of isoflavones, the HR was 0.89 (95% CI: 0.83, 0.96; P for trend=0.009). Inverse associations were also found for consumption of major individual isoflavones, including daidzein and genistein, with risk of T2D. CONCLUSIONS: Intake of isoflavones was associated with a modestly lower T2D risk in US men and women who typically consumed low-to-moderate amounts of soy foods. These findings warrant replications in other populations with similar soy intake levels.

Common variation in BRCA1 may have a role in progression to lethal prostate cancer after radiation treatment.

BACKGROUND: To evaluate whether single-nucleotide polymorphisms (SNPs) reflecting common variation in the tumor suppressor BRCA1 affect prostate cancer outcomes. Because radiation therapy (RT) induces DNA damage, we hypothesized that common variation in BRCA1 has a role in progression to lethal prostate cancer, particularly in patients receiving RT. METHODS: We followed 802 men diagnosed with localized prostate cancer (cT1-T3/N0/M0) who were treated with RT in the US Health Professionals Follow-up Study (HPFS) and Physicians' Health Study (PHS), for progression to lethal prostate cancer. Six SNPs (rs3737559, rs1799950, rs799923, rs915945, rs4474733 and rs8176305) were genotyped in HPFS to capture common variation across BRCA1. rs4474733 and rs8176305 were also evaluated in the PHS cohort. Cox proportional hazards models were used to estimate per-allele hazard ratios (HR) and 95% confidence intervals (CI) stratified by primary treatment. RESULTS: In the RT group (n=802), 71 men progressed to lethal disease during a mean follow-up of 12 years. We found that two SNPs, rs4473733 (HR: 0.65; 95% CI 0.42-0.99) and rs8176305 (HR: 2.03; 95% CI 1.33-3.10), were associated with lethal prostate cancer in men receiving RT. CONCLUSIONS: Common variation in BRCA1 may influence clinical outcomes in patients receiving RT for localized prostate cancer by modifying the response to RT. Our findings merit further follow-up studies to validate these SNPs and better understand their functional and biological significance.

Male pattern baldness and risk of colorectal neoplasia.

BACKGROUND: Male pattern baldness is positively associated with androgens as well as insulin-like growth factor 1 (IGF-1) and insulin, all of which are implicated in pathogenesis of colorectal neoplasia. METHODS: From 1992 through 2010, we prospectively followed participants in the Health Professionals Follow-Up Study. Hair pattern at age 45 years was assessed at baseline with five image categories (no baldness, frontal-only baldness, frontal-plus-mild-vertex baldness, frontal-plus-moderate-vertex baldness, and frontal-plus-severe-vertex baldness). Cancer analysis included 32 782 men and used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Restricted to men who underwent at least one endoscopy over the study period, adenoma analysis included 29 770 men and used logistic regressions for clustered data to estimate odds ratios (ORs) and 95% CIs. RESULTS: Over the mean follow-up of 15.6 years, 710 cases of colorectal cancer (478 for colon, 152 for rectum, and 80 unknown site) developed. Significantly increased risks associated with frontal-only baldness and frontal-plus-mild-vertex baldness relative to no baldness were observed for colon cancer with respective HR being 1.29 (95% CI, 1.03-1.62) and 1.31 (95% CI, 1.01-1.70). Over the 19-year study period, 3526 cases of colorectal adenoma were detected. Evidence for an increased risk of colorectal adenoma relative to no baldness was significant with frontal-only baldness (OR, 1.16; 95% CI, 1.06-1.26) and borderline insignificant with frontal-plus-severe-vertex baldness (OR, 1.14; 95% CI, 0.98-1.33). CONCLUSIONS: Subtypes of male pattern baldness at age 45 years were positively associated with colorectal neoplasia. Future studies are warranted to confirm our results and to determine the predictive value of male pattern baldness to identify those at high risk for colorectal neoplasia.

Periodontal disease and risk of all cancers among male never smokers: an updated analysis of the Health Professionals Follow-up Study.

BACKGROUND: Periodontal disease has a direct impact on the immune response and has been linked to several chronic diseases, including atherosclerosis and stroke. Few studies have examined the association between periodontal disease and cancer. PATIENTS AND METHODS: A total of 19 933 men reported being never smokers (of cigarette, pipes or cigars) in the Health Professionals' Follow-up Study. Periodontal disease status and teeth number were self-reported at baseline and during follow-up. All cancers were ascertained during 26 years of follow-up. Cox's proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) adjusting for risk factors. RESULTS: A 13% increase in total cancer was observed among men reporting periodontitis at baseline, and a 45% increase in risk was observed among men with advanced periodontitis (periodontitis with <17 remaining teeth). Periodontitis was not associated with prostate cancer, colorectal cancer or melanoma, the three most common cancers in this cohort of never smokers, but a 33% increase in risk was observed for smoking-related cancers (lung, bladder, oropharnygeal, esophageal, kidney, stomach and liver cancers; HR = 1.33, 95% CI 1.07-1.65). Men with advanced periodontitis had an HR of 2.57 (95% CI 1.56-4.21; P = 0.0002) for smoking-related cancers, compared with men who did not have periodontitis and had 17 teeth or more. Advanced periodontitis was associated with elevated risks of esophageal and head and neck cancers (HR = 6.29, 95% CI 2.13-18.6; based on five cases with advanced periodontitis) and bladder cancer (HR = 5.06, 95% CI 2.32-11.0; based on nine cases with advanced periodontitis). CONCLUSIONS: Advanced periodontitis was associated with a 2.5-fold increase in smoking-related cancers among never smokers. Periodontitis may impact cancer risk through system immune dysregulation. Further studies need to examine the immune impact of advanced periodontitis on cancer, especially for cancers known to be caused by smoking.

Nut consumption and risk of colorectal cancer in women.

BACKGROUND/OBJECTIVES: Increasing nut consumption has been associated with reduced risk of obesity and type II diabetes, the risk factors for colorectal cancer. However, the association between nut consumption and colorectal cancer risk is unclear. We aimed to examine the association of long-term nut consumption with risk of colorectal cancer. SUBJECTS/METHODS: We prospectively followed 75,680 women who were free of cancer at baseline in the Nurses' Health Study, and examined the association between nut consumption and colorectal cancer risk. Nut consumption was assessed at baseline and updated every 2-4 years. Relative risks (RRs) and 95% confidence intervals (95% CIs) were estimated using Cox proportional hazards models. RESULTS: During 2,103,037 person-years of follow-up, we identified 1503 colorectal cancer cases. After adjustment for other known or suspected risk factors, women who consumed nuts 2 or more times per week (that is, ⩾ 56 g per week) had a 13% lower risk of colorectal cancer compared with those who rarely consumed nuts, but the association was not statistically significant (RR: 0.87; 95% CI: 0.72-1.05; P-trend: 0.06). No association was observed for peanut butter. CONCLUSIONS: In this large prospective cohort of women, frequent nut consumption was not significantly associated with colorectal cancer risk after adjusting for other risk factors.

Egg intake and cancers of the breast, ovary and prostate: a dose-response meta-analysis of prospective observational studies.

Evidence suggests that egg intake may be implicated in the aetiology of sex hormone-related cancers. However, dose-response relationships between egg intake and such cancers are unclear. Thus, we conducted a dose-response meta-analysis to summarise the dose-response relationships between egg consumption and the risk of breast, prostate and gynaecological cancers. A literature search was performed using PubMed and Embase up to April 2015 to identify relevant prospective observational studies. Summary relative risk (RR) and 95% CI were estimated using a random-effects model. For breast cancer, the linear dose-response meta-analysis found a non-significantly increased risk (RR for an increase of 5 eggs consumed/week: 1·05, 95% CI 0·99, 1·11, n 16,023 cases). Evidence for non-linearity was not statistically significant (P non-linearity= 0·50, n 15,415 cases) but consuming ≥ 5 eggs/week was significantly associated with an increased risk of breast cancer compared with no egg consumption, with the summary RR being 1·04 (95% CI 1·01, 1·07) for consuming 5 eggs/week and 1·09 (95% CI 1·03, 1·15) for consuming about 9 eggs/week. For other cancers investigated, the summary RR for an increase of 5 eggs consumed/week was 1·09 (95% CI 0·96, 1·24, n 2636 cases) for ovarian cancer; 1·47 (95% CI 1·01, 2·14, n 609 cases) for fatal prostate cancer, with evidence of small-study effects (P Egger= 0·04). No evidence was found for an association with the risk of total prostate cancer. While our conclusion was tempered by the potential for publication bias and confounding, high egg intake may be associated with a modestly elevated risk of breast cancer, and a positive association between egg intake and ovarian and fatal prostate cancers cannot be ruled out.

Television watching and risk of colorectal adenoma.

BACKGROUND: Prolonged TV watching, a major sedentary behaviour, is associated with increased risk of obesity and diabetes and may involve in colorectal carcinogenesis. METHODS: We conducted a cross-sectional analysis among 31 065 men with ⩾1 endoscopy in the Health Professionals Follow-up Study (1988-2008) to evaluate sitting while watching TV and its joint influence with leisure-time physical activity on risk of colorectal adenoma. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Prolonged sitting while watching TV was significantly associated with increased risk of colorectal adenoma (n=4280), and adjusting for physical activity or a potential mediator body mass index did not change the estimates. The ORs (95% CIs) across categories of TV watching (0-6, 7-13, 14-20, and 21+ h per week) were 1.00 (referent), 1.09 (1.01-1.17), 1.16 (1.06-1.27), and 1.10 (0.97-1.25) (OR per 14-h per week increment=1.11; 95% CI: 1.04-1.18; Ptrend=0.001). Compared with the least sedentary (0-6 h per week of TV) and most physically active (highest quintile) men, the most sedentary (14+ h per week) and least active (lowest quintile) men had a significant increased risk of adenoma (OR=1.25; 95% CI: 1.05-1.49), particularly for high-risk adenoma. CONCLUSIONS: Prolonged TV viewing is associated with modest increased risk of colorectal adenoma independent of leisure-time physical activity and minimally mediated by obesity.