Search

Background The incidence of differentiated thyroid cancer (DTC) is higher in women than in men but whether sex steroid hormones contribute to this difference remains unclear. Studies of reproductive and hormonal factors and thyroid cancer risk have provided inconsistent results. Methods Original data from 1 252 907 women in 16 cohorts in North America, Europe, Australia and Asia were combined to evaluate associations of DTC risk with reproductive and hormonal factors. Multivariable-adjusted Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% CIs. Results During follow-up, 2142 women were diagnosed with DTC. Factors associated with higher risk of DTC included younger age at menarche (<10 vs 10–11 years; HR, 1.28; 95% CI, 1.00–1.64), younger (<40; HR, 1.31; 95% CI, 1.05–1.62) and older (≥55; HR, 1.33; 95% CI, 1.05–1.68) ages at menopause (vs 40–44 years), ever use of menopausal hormone therapy (HR, 1.16; 95% CI, 1.02–1.33) and previous hysterectomy (HR, 1.25; 95% CI, 1.13–1.39) or bilateral oophorectomy (HR, 1.14; 95% CI, 1.00–1.29). Factors associated with lower risk included longer-term use (≥5 vs <5 years) of oral contraceptives (HR, 0.86; 95% CI, 0.76–0.96) among those who ever used oral contraception and baseline post-menopausal status (HR, 0.82; 95% CI, 0.70–0.96). No associations were observed for parity, duration of menopausal hormone therapy use or lifetime number of reproductive years or ovulatory cycles. Conclusions Our study provides some evidence linking reproductive and hormonal factors with risk of DTC. Results should be interpreted cautiously considering the modest strength of the associations and potential for exposure misclassification and detection bias. Prospective studies of pre-diagnostic circulating sex steroid hormone measurements and DTC risk may provide additional insight. [ABSTRACT FROM AUTHOR]

Thyroid cancer incidence and the prevalence of overweight and obesity are increasing, but the future thyroid cancer burden attributable to contemporary levels of overweight and obesity has not been evaluated before. We quantified this burden in Australia, and assessed whether the overweight/obesity‐attributable burden differed by sex or other population subgroupings. We estimated the strength of the associations of overweight and obesity with thyroid cancer with adjusted proportional hazards models using pooled data from seven Australian cohorts (N = 367 058) with 431 thyroid cancer cases ascertained from linked national cancer registry data during a maximum 22‐year follow‐up. We combined these estimates with nationally representative 2017 to 2018 estimates of overweight and obesity prevalence to estimate population attributable fractions (PAFs) of future thyroid cancers attributable to overweight and obesity, accounting for competing risk of death, and compared PAFs for population subgroups. Contemporary levels of overweight and obesity explain 18.6% (95% confidence interval [CI] = 5.2%‐30.2%), and obesity alone 13.7% (95% CI: 5.2%‐21.4%), of the future thyroid cancer burden. The obesity‐attributable thyroid cancer burden is 21.4% (95% CI: 2.8%‐36.5%) for men and 10.1% (95% CI: 0.8%‐18.6%) for women. Were the currently obese overweight instead, 9.9% (95% CI: 1.0%‐18.1%) of thyroid cancers could be avoided. The relative overweight/obesity‐attributable burden is higher for those consuming on average more than two alcoholic drinks per day (63.4%) and for those who are not married/co‐habiting (33.2%). In conclusion, avoiding excess weight, especially obesity, should be a priority for thyroid cancer prevention. Further studies, with findings stratified by tumour size, may reveal the potential role of overdiagnosis in our results. What's new? As the incidence of thyroid cancer has increased, questions have arisen regarding possible associations with increasing incidence of overweight and obesity. Here, the authors projected the future burden of thyroid cancer in Australia with regard to incidence of overweight and obesity. Analyses show that current levels of overweight and obesity in Australia explain about 19% of future thyroid cancers, with 14% of cancers attributed to obesity alone. Moreover, if currently obese individuals were instead overweight, nearly 10% of thyroid cancers could be avoided. The findings suggest that many thyroid cancers could be prevented through improved weight management. [ABSTRACT FROM AUTHOR]

Estimates of the future breast cancer burden preventable through modifications to current behaviours are lacking. We assessed the effect of individual and joint behaviour modifications on breast cancer burden for premenopausal and postmenopausal Australian women, and whether effects differed between population subgroups. We linked pooled data from six Australian cohort studies (n = 214,536) to national cancer and death registries, and estimated the strength of the associations between behaviours causally related to cancer incidence and death using adjusted proportional hazards models. We estimated exposure prevalence from representative health surveys. We combined these estimates to calculate Population Attributable Fractions (PAFs) with 95% confidence intervals (CIs), and compared PAFs for population subgroups. During the first 10 years follow‐up, there were 640 incident breast cancers for premenopausal women, 2,632 for postmenopausal women, and 8,761 deaths from any cause. Of future breast cancers for premenopausal women, any regular alcohol consumption explains 12.6% (CI = 4.3–20.2%), current use of oral contraceptives for ≥5 years 7.1% (CI = 0.3–13.5%), and these factors combined 18.8% (CI = 9.1–27.4%). Of future breast cancers for postmenopausal women, overweight or obesity (BMI ≥25 kg/m2) explains 12.8% (CI = 7.8–17.5%), current use of menopausal hormone therapy (MHT) 6.9% (CI = 4.8–8.9%), any regular alcohol consumption 6.6% (CI = 1.5–11.4%), and these factors combined 24.2% (CI = 17.6–30.3%). The MHT‐related postmenopausal breast cancer burden varied by body fatness, alcohol consumption and socio‐economic status, the body fatness‐related postmenopausal breast cancer burden by alcohol consumption and educational attainment, and the alcohol‐related postmenopausal breast cancer burden by breast feeding history. Our results provide evidence to support targeted and population‐level cancer control activities. What's new? While several potentially‐modifiable behavioural risk factors have been identified for breast cancer, estimates of the preventable future breast cancer burden are still lacking. Based on a large prospective pooled Australian cohort, here the authors reveal that regular alcohol consumption is the leading modifiable cause of breast cancer burden for premenopausal women (12.6%). Using the latest exposure prevalence information, the authors rank body fatness as the leading cause of preventable breast cancer burden for postmenopausal women (12.8%), with regular alcohol consumption also contributing substantially (6.6%). The findings provide evidence to support targeted and population‐level cancer control activities in Australia and beyond. [ABSTRACT FROM AUTHOR]

Objective: To investigate relationships between mortality and circulating 25-hydroxyvitamin D (25(OH)D), 25-hydroxycholecalciferol (25(OH)D3) and 25-hydroxyergocalciferol (25(OH)D2).Design: Case-cohort study within the Melbourne Collaborative Cohort Study (MCCS). We measured 25(OH)D2 and 25(OH)D3 in archived dried blood spots by LC-MS/MS. Cox regression was used to estimate mortality hazard ratios (HR), with adjustment for confounders.Setting: General community.Subjects: The MCCS included 29 206 participants, who at recruitment in 1990-1994 were aged 40-69 years, had dried blood spots collected and no history of cancer. For the present study we selected participants who died by 31 December 2007 (n 2410) and a random sample (sub-cohort, n 2996).Results: The HR per 25 nmol/l increment in concentration of 25(OH)D and 25(OH)D3 were 0·86 (95 % CI 0·78, 0·96; P=0·007) and 0·85 (95 % CI 0·77, 0·95; P=0·003), respectively. Of 5108 participants, sixty-three (1·2 %) had detectable 25(OH)D2; their mean 25(OH)D concentration was 11·9 (95 % CI 7·3, 16·6) nmol/l higher (P<0·001). The HR for detectable 25(OH)D2 was 1·80 (95 % CI 1·09, 2·97; P=0·023); for those with detectable 25(OH)D2, the HR per 25 nmol/l increment in 25(OH)D was 1·06 (95 % CI 0·87, 1·29; P interaction=0·02). HR were similar for participants who reported being in good, very good or excellent health four years after recruitment.Conclusions: Total 25(OH)D and 25(OH)D3 concentrations were inversely associated with mortality. The finding that the inverse association for 25(OH)D was restricted to those with no detectable 25(OH)D2 requires confirmation in populations with higher exposure to ergocalciferol. [ABSTRACT FROM AUTHOR]

Background: Associations between anthropometry and head and neck cancer (HNC) risk are inconsistent. We aimed to evaluate these associations while minimizing biases found in previous studies. Methods: We pooled data from 1 941 300 participants, including 3760 cases, in 20 cohort studies and used multivariable-adjusted Cox proportional hazard regression models to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association of anthropometric measures with HNC risk overall and stratified by smoking status. Results: Greater waist circumference (per 5cm: HR=1.04, 95% CI 1.03-1.05, P-value for trend=<0.0001) and waist-to-hip ratio (per 0.1 unit: HR=1.07, 95% CI 1.05-1.09, P-value for trend=<0.0001), adjusted for body mass index (BMI), were associated with higher risk and did not vary by smoking status (P-value for heterogeneity=0.85 and 0.44, respectively). Associations with BMI (P-value for interaction=<0.0001) varied by smoking status. Larger BMI was associated with higher HNC risk in never smokers (per 5 kg/m2: HR=1.15, 95% CI 1.06-1.24, P-value for trend=0.0006), but not in former smokers (per 5 kg/m2: HR=0.99, 95% CI 0.93-1.06, P-value for trend=0.79) or current smokers (per 5 kg/m2: HR=0.76, 95% CI 0.71-0.82, P-value for trend=<0.0001). Larger hip circumference was not associated with a higher HNC risk. Greater height (per 5cm) was associated with higher risk of HNC in never and former smokers, but not in current smokers. Conclusions: Waist circumference and waist-to-hip ratio were associated positively with HNC risk regardless of smoking status, whereas a positive association with BMI was only found in never smokers. [ABSTRACT FROM AUTHOR]

Evidence on the endometrial and ovarian cancer burden preventable through modifications to current causal behavioural and hormonal exposures is limited. Whether the burden differs by population subgroup is unknown. We linked pooled data from six Australian cohort studies to national cancer and death registries, and quantified exposure-cancer associations using adjusted proportional hazards models. We estimated exposure prevalence from representative health surveys. We then calculated Population Attributable Fractions (PAFs) with 95% confidence intervals (CIs), accounting for competing risk of death, and compared PAFs for population subgroups. During a median 4.9 years follow-up, 510 incident endometrial and 303 ovarian cancers were diagnosed. Overweight and obesity explained 41.9% (95% CI 32.3–50.1) of the endometrial cancer burden and obesity alone 34.5% (95% CI 27.5–40.9). This translates to 12,800 and 10,500 endometrial cancers in Australia in the next 10 years, respectively. The body fatness-related endometrial cancer burden was highest (49–87%) among women with diabetes, living remotely, of older age, lower socio-economic status or educational attainment and born in Australia. Never use of oral contraceptives (OCs) explained 8.1% (95% CI 1.8–14.1) or 2500 endometrial cancers. A higher BMI and current long-term MHT use increased, and long-term OC use decreased, the risk of ovarian cancer, but the burden attributable to overweight, obesity or exogenous hormonal factors was not statistically significant. Excess body fatness, a trait that is of high and increasing prevalence globally, is responsible for a large proportion of the endometrial cancer burden, indicating the need for effective strategies to reduce adiposity. • Contemporary estimates of endometrial cancer burden attributable to body fatness. • Overweight and obesity explain 42%, and obesity alone explains 35% of endometrial cancers. • First estimates of future endometrial cancer burden for population subgroups. • Overweight and obesity explain 49–87% of the endometrial cancer burden for some subgroups of women. [ABSTRACT FROM AUTHOR]