Search

Background: After adjusting for age and body mass index (BMI), mammographic measures—dense area (DA), percent dense area (PDA), and nondense area (NDA)—are associated with breast cancer risk. Our aim was to use longitudinal data to estimate the extent to which these risk-predicting measures track over time. Methods: We collected 4,320 mammograms (age range, 24–83 years) from 970 women in the Melbourne Collaborative Cohort Study and the Australian Breast Cancer Family Registry. Women had on average 4.5 mammograms (range, 1–14). DA, PDA, and NDA were measured using the Cumulus software and normalized using the Box–Cox method. Correlations in the normalized risk-predicting measures over time intervals of different lengths were estimated using nonlinear mixed-effects modeling of Gompertz curves. Results: Mean normalized DA and PDA were constant with age to the early 40s, decreased over the next two decades, and were almost constant from the mid-60s onward. Mean normalized NDA increased nonlinearly with age. After adjusting for age and BMI, the within-woman correlation estimates for normalized DA were 0.94, 0.93, 0.91, 0.91, and 0.91 for mammograms taken 2, 4, 6, 8, and 10 years apart, respectively. Similar correlations were estimated for the age- and BMI-adjusted normalized PDA and NDA. Conclusions: The mammographic measures that predict breast cancer risk are highly correlated over time. Impact: This has implications for etiologic research and clinical management whereby women at increased risk could be identified at a young age (e.g., early 40s or even younger) and recommended appropriate screening and prevention strategies. Cancer Epidemiol Biomarkers Prev; 26(4); 651–60. ©2017 AACR.

Background: Adult weight is positively associated with postmenopausal breast cancer but few studies have investigated whether there are associations with weight and body mass index (BMI) in early adulthood, or subsequent weight change. Methods: A total of 14,441 postmenopausal women from the Melbourne Collaborative Cohort Study (MCCS) were followed for 16.5 years (mean) and 668 incident breast cancers were identified. Hazard ratios (HRs) were estimated using Cox regression. Results: Weight and BMI at 18 to 21 years were not associated with risk of any type of breast cancer and there was no variation by age. Women with the greatest increase in weight and BMI had higher risk at older ages [HR per 5 kg/m2 gain in BMI = 1.24; 95% confidence interval (CI), 1.11–1.40], although the test for homogeneity by age was not significant. At older ages, the association was stronger for progesterone (PR) positive disease compared with PR negative disease (HR per 5 kg/m2 gain in BMI, 1.43; 95% CI, 1.23–1.66; test for homogeneity by PR status, P < 0.01) and for diseases that were positive for both estrogen (ER) and PR (HR per 5 kg/m2 gain in BMI, 1.45; 95% CI, 1.24–1.69; test for homogeneity by ER/PR status, P = 0.02). HRs were also greater for HER2− and luminal A tumors, but the P values for homogeneity by tumor subgroups were not significant. Conclusion: Early adulthood weight is not associated with risk of postmenopausal breast cancer. Greater weight gain during adulthood might be associated with increased risk for older women (>69 years) and this association might vary by tumor hormone receptor status. Impact: Further studies need to investigate the impact of increase in weight during adulthood on postmenopausal breast cancer risk and the potential variation by age or tumor characteristics. Cancer Epidemiol Biomarkers Prev; 22(8); 1409–16. ©2013 AACR.

Background: Epidemiologic studies have consistently reported positive associations between obesity and colon cancer risk for men, but the evidence is less consistent for women. Few studies have investigated effects of weight change on colon cancer risk. Methods: Using the Melbourne Collaborative Cohort Study, which recruited men and women mostly in 40 to 69 years of age, we investigated associations between weight and body mass index (BMI) at age 18 years and at study entry and weight change since age 18 years and colon cancer. Hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox regression. Results: During follow-up of 16,188 men and 23,438 women for 14 years on average, we ascertained 569 incident colon cancers. Weight and BMI at study entry were positively associated with colon cancer risk for men [HR, 1.12 (95% CI, 1.04-1.21) per 5-kg increment; HR, 1.39 (95% CI, 1.12-1.71) per 5 kg/m2], but not women. Risk of colon cancer was not associated with weight or BMI at age 18 years. Adult weight change was positively associated with colon cancer risk for men (HR, 1.11 per 5-kg increment; 95% CI, 1.03-1.20), but not women (HR, 1.00; 95% CI, 0.94-1.07). Men who gained ≥20 kg from age 18 had an increased risk of colon cancer compared with men whose weight was stable (HR, 1.47; 95% CI, 0.94-2.31). Conclusion: Weight gain during adult life increases men's risk of colon cancer. Impact: Avoiding excessive weight gain might help reduce colon cancer risk for men. Cancer Epidemiol Biomarkers Prev; 19(11); 2978–86. ©2010 AACR.

Epidemiologic studies have consistently reported that endogenous steroid hormone levels are associated with postmenopausal breast cancer risk, but little is known on the associations by tumor grade, hormone receptor status, or age at diagnosis.We performed a case-cohort study of naturally postmenopausal women within the Melbourne Collaborative Cohort Study that included a random sample of 857 women and 197 breast cancer cases diagnosed during a mean of 9.2 years of follow-up. Concentrations of total estradiol, estrone sulfate, testosterone, DHEA sulfate, androstenedione, and sex hormone binding globulin were measured in plasma collected at baseline before diagnosis; free estradiol plasma concentration was calculated. Cox regression was used to estimate associations adjusted for known and potential confounders.The HR for breast cancer comparing fourth and first quartiles was 1.44 [95% confidence interval (95% CI), 0.89-2.35] for total estradiol, 1.75 (95% CI, 1.06, 2.89) for free estradiol, 2.05 (95% CI, 1.24-3.37) for estrone sulfate, 1.25 (95% CI, 0.78-2.01) for testosterone, 1.41 (95% CI, 0.88-2.27) for DHEA sulfate, 1.49 (95% CI, 0.91-2.44) for androstenedione, and 0.33 (95% CI, 0.19-0.55) for sex hormone binding globulin. These associations did not differ by tumor grade and estrogen receptor/progesterone receptor status (all test for heterogeneity, P > 0.05). Risks associated with estrogen and androgen levels were stronger at older ages (test for interaction across age groups, P = 0.59 for total estradiol and P = 0.01 for testosterone).Our prospective study confirms earlier findings and suggests that the associations of endogenous hormones with postmenopausal breast cancer risk are independent of tumor grade, and hormone receptor status and might increase in strength with age. Cancer Epidemiol Biomarkers Prev; 19(2); 492–502