Melbourne School of Population and Global Health - Research Publications
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ItemBreast cancer screening of women aged 70-74 years: results from a natural experiment across Australia(SPRINGER, 2014-01)There is a lack of evidence regarding the optimal age at which to cease mammographic screening for breast cancer. This ecological study compared Australian state and territory level screening participation rates and cancer outcomes from 1996 to 2005 to identify the extent to which screening women aged 70-74 results in smaller, earlier stage breast cancers. With each 10 % absolute increase in screening participation, there was no significant difference in cancer incidence, but the incidence of large cancers was 8 % lower (IRR = 0.92, 95 % CI 0.90-0.94, p < 0.001); there was some evidence of reduced nodal involvement at diagnosis (IRR 0.97, 95 % CI 0.95-0.99, p = 0.004) but this estimate was sensitive to assumptions regarding missing data. Increased mammographic screening of women aged 70-74 years reduces the incidence of large (>15 mm) cancers-and possibly cancers with nodal involvement-without a concomitant increase in overall cancer incidence.
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ItemNo Preview AvailableScreening and Breast Cancer Mortality-Response(AMER ASSOC CANCER RESEARCH, 2012-12)
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ItemAutoDensity: an automated method to measure mammographic breast density that predicts breast cancer risk and screening(BMC, 2013)INTRODUCTION: While Cumulus - a semi-automated method for measuring breast density - is utilised extensively in research, it is labour-intensive and unsuitable for screening programmes that require an efficient and valid measure on which to base screening recommendations. We develop an automated method to measure breast density (AutoDensity) and compare it to Cumulus in terms of association with breast cancer risk and breast cancer screening outcomes. METHODS: AutoDensity automatically identifies the breast area in the mammogram and classifies breast density in a similar way to Cumulus, through a fast, stand-alone Windows or Linux program. Our sample comprised 985 women with screen-detected cancers, 367 women with interval cancers and 4,975 controls (women who did not have cancer), sampled from first and subsequent screening rounds of a film mammography screening programme. To test the validity of AutoDensity, we compared the effect estimates using AutoDensity with those using Cumulus from logistic regression models that tested the association between breast density and breast cancer risk, risk of small and large screen-detected cancers and interval cancers, and screening programme sensitivity (the proportion of cancers that are screen-detected). As a secondary analysis, we report on correlation between AutoDensity and Cumulus measures. RESULTS: AutoDensity performed similarly to Cumulus in all associations tested. For example, using AutoDensity, the odds ratios for women in the highest decile of breast density compared to women in the lowest quintile for invasive breast cancer, interval cancers, large and small screen-detected cancers were 3.2 (95% CI 2.5 to 4.1), 4.7 (95% CI 3.0 to 7.4), 6.4 (95% CI 3.7 to 11.1) and 2.2 (95% CI 1.6 to 3.0) respectively. For Cumulus the corresponding odds ratios were: 2.4 (95% CI 1.9 to 3.1), 4.1 (95% CI 2.6 to 6.3), 6.6 (95% CI 3.7 to 11.7) and 1.3 (95% CI 0.9 to 1.8). Correlation between Cumulus and AutoDensity measures was 0.63 (P < 0.001). CONCLUSIONS: Based on the similarity of the effect estimates for AutoDensity and Cumulus inmodels of breast density and breast cancer risk and screening outcomes, we conclude that AutoDensity is a valid automated method for measuring breast density from digitised film mammograms.
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ItemNo Preview AvailableMammographic Screening and Breast Cancer Mortality: A Case-Control Study and Meta-analysis(AMER ASSOC CANCER RESEARCH, 2012-09)BACKGROUND: Observational studies are necessary to assess the impact of population screening on breast cancer mortality. While some ecological studies have notably found little or no association, case-control studies consistently show strong inverse associations, but they are sometimes ignored, perhaps due to theoretical biases arising from the study design. We conducted a case-control study of breast cancer deaths in Western Australia to evaluate the effect of participation in the BreastScreen Australia program, paying particular attention to potential sources of bias, and undertook an updated meta-analysis of case-control studies. METHODS: Our study included 427 cases (women who died from breast cancer), each matched to up to 10 controls. We estimated the association between screening participation and breast cancer mortality, quantifying the effect of potential sources of bias on our findings, including selection bias, information bias, and confounding. We also conducted a meta-analysis of published case-control studies. RESULTS: The OR for participation in the Western Australian BreastScreen program in relation to death from breast cancer was 0.48 [95% confidence interval (CI), 0.38-0.59; P < 0.001]. We were unable to identify biases that could negate this finding: sensitivity analyses generated ORs from 0.45 to 0.52. Our meta-analysis yielded an OR of 0.51 (95% CI, 0.46-0.55). CONCLUSIONS: Our findings suggest an average 49% reduction in breast cancer mortality for women who are screened. In practice, theoretical biases have little effect on estimates from case-control studies. IMPACT: Case-control studies, such as ours, provide robust and consistent evidence that screening benefits women who choose to be screened.
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ItemThe feasibility of routinely collecting detailed information about menopausal history and menopause therapy use from women participating in Australian State and Territory BreastScreen programs(Australasian Epidemiological Association, 2007)Use of menopause therapies such as hormone therapies (HT) is associated with reduced mammographic sensitivity and screening effectiveness, and there is some suggestion that this differs according to HT formulation.At this time, the Victorian arm of the Australian breast cancer screening program (BreastScreen Victoria) collects some information about HT use at each screen, without detail about HT type or other menopause therapies. We examine the feasibility of extending the information collected to include more detailed information about the use of prescribed and non-prescribed menopause therapies, as well as the age at onset of menopause, reasoning that such data collection would generate a large database that could be used to further investigate the role of menopause therapy use and menopause in screening performance. We find that women show good recall of most information, except menopause therapy product name, which was recalled well only for formulations ceased up to two years prior to survey. We conclude that routine collection of this information is feasible within the biennial screening program.