Yaojen Chang

Publications (2)6.52 Total impact

• Article: Collaborative modeling of the impact of obesity on race-specific breast cancer incidence and mortality.

  Yaojen Chang, Clyde B Schechter, Nicolien T van Ravesteyn, Aimee M Near, Eveline A M Heijnsdijk, Lucile Adams-Campbell, David Levy, Harry J de Koning, Jeanne S Mandelblatt
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  ABSTRACT: Obesity affects multiple points along the breast cancer control continuum from prevention to screening and treatment, often in opposing directions. Obesity is also more prevalent in Blacks than Whites at most ages so it might contribute to observed racial disparities in mortality. We use two established simulation models from the Cancer Intervention and Surveillance Modeling Network (CISNET) to evaluate the impact of obesity on race-specific breast cancer outcomes. The models use common national data to inform parameters for the multiple US birth cohorts of Black and White women, including age- and race-specific incidence, competing mortality, mammography characteristics, and treatment effectiveness. Parameters are modified by obesity (BMI of ≥30 kg/m(2)) in conjunction with its age-, race-, cohort- and time-period-specific prevalence. We measure age-standardized breast cancer incidence and mortality and cases and deaths attributable to obesity. Obesity is more prevalent among Blacks than Whites until age 74; after age 74 it is more prevalent in Whites. The models estimate that the fraction of the US breast cancer cases attributable to obesity is 3.9-4.5 % (range across models) for Whites and 2.5-3.6 % for Blacks. Given the protective effects of obesity on risk among women <50 years, elimination of obesity in this age group could increase cases for both the races, but decrease cases for women ≥50 years. Overall, obesity accounts for 4.4-9.2 % and 3.1-8.4 % of the total number of breast cancer deaths in Whites and Blacks, respectively, across models. However, variations in obesity prevalence have no net effect on race disparities in breast cancer mortality because of the opposing effects of age on risk and patterns of age- and race-specific prevalence. Despite its modest impact on breast cancer control and race disparities, obesity remains one of the few known modifiable risks for cancer and other diseases, underlining its relevance as a public health target.
  Breast Cancer Research and Treatment 10/2012; · 4.43 Impact Factor
• Article: Modeling the impact of population screening on breast cancer mortality in the United States.

  Jeanne S Mandelblatt, Kathleen A Cronin, Donald A Berry, Yaojen Chang, Harry J de Koning, Sandra J Lee, Sylvia K Plevritis, Clyde B Schechter, Natasha K Stout, Nicolien T van Ravesteyn, Marvin Zelen, Eric J Feuer
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  ABSTRACT: Optimal US screening strategies remain controversial. We use six simulation models to evaluate screening outcomes under varying strategies. The models incorporate common data on incidence, mammography characteristics, and treatment effects. We evaluate varying initiation and cessation ages applied annually or biennially and calculate mammograms, mortality reduction (vs. no screening), false-positives, unnecessary biopsies and over-diagnosis. The lifetime risk of breast cancer death starting at age 40 is 3% and is reduced by screening. Screening biennially maintains 81% (range 67% to 99%) of annual screening benefits with fewer false-positives. Biennial screening from 50-74 reduces the probability of breast cancer death from 3% to 2.3%. Screening annually from 40 to 84 only lowers mortality an additional one-half of one percent to 1.8% but requires substantially more mammograms and yields more false-positives and over-diagnosed cases. Decisions about screening strategy depend on preferences for benefits vs. potential harms and resource considerations.
  Breast (Edinburgh, Scotland) 10/2011; 20 Suppl 3:S75-81. · 2.09 Impact Factor