Table 2.

Examples of simulation model input parameters and multilevel influences^*

Parameter	Description	Conditional on	Levels that influence parameter
Incidence from age–period–cohort model	Incidence	Age, race, breast density, birth cohort	Ecological forces that affect risk behavior (eg, reproductive forces, trends in smoking post-WWII) Ecological factors that affect hormonal exposures Individual-level factors affecting risk such as family history and diet
Population birth distribution	Probability distribution of birth-years in US population	Race	Ecological factors affecting diffusion of contraception; policies about use of contraception
Non-breast cancer mortality	All-cause mortality exclusive of deaths from breast cancer	Race, age, birth cohort	Ecological factors affecting mortality such as occupations, insurance Individual factors related to social class, health habits
Unscreened stage (or tumor size) distribution	Distribution of stages (or sizes) of tumors diagnosed in the absence of screening	Race, age	Biological scale factors related to cellular and molecular aspects of cancer progression
Dwell-time distributions	Mean in stage and in preclinical state (sojourn time)	Age	Unobservable biological level of cellular and molecular events Interactions of biological levels with individual-level health behaviors and exposures that may modify biological processes
Screened stage distribution	Distribution of stages of tumors that are screen-diagnosed by each test	Race, age, and first-vs-later screen	Ecological factors affecting structure of care, policies regarding insurance coverage, and access to screening and diagnostic services Individual factors related to adherence to screening use and diagnostic follow-up Biological level related to ability of technology to detect tissue changes related to cancer
Screening dissemination	Distribution by cohort, age, time period	Cohort, age, calendar year	Ecological factors affecting structure of care, policies regarding insurance coverage, and access to screening and diagnostic services Individual factors related to adherence to screening use and diagnostic follow-up
Operating characteristics	Sensitivity and specificity, initial and later screens	Race, age, tumor size, density	Ecological-level factors that affect the quality of screening facilities Population level related to training and skill of radiologists Biological level related to ability of technology to detect tissue changes related to cancer
Screening-induced care	Biopsies and other diagnostic tests	Age	Ecological level in access to care Individual level in adherence and health seeking behaviors
HR/HER2 distribution	Probabilities of tumors exhibiting ER and HER2 positivity	Race, age, stage/size at diagnosis	Individual level in health behaviors increasing risk of particular tumors (largely unknown at present) Biological level of cellular and genetic processes that lead to different types of tumors
Treatment dissemination	Probability distribution of treatment regimens	Race, age, year, stage, ER/HER2	Ecological level in access to care Individual level in adherence and health-seeking behaviors
Natural history survival	Survival functions before use of adjuvant Rx	Race, age, stage	Biological level of unobservable natural history of disease in the absence of intervention
Treatment effectiveness	Hazard ratios for regimens; modifies survival without Rx	Race, age, Rx, stage, ER/HER2	Ecological level in access to treatment and quality of treatment Individual level in adherence to treatment regimen Biological levels of effects of treatments on cellular and molecular processes of carcinogenesis and metastasis
Quality of life	Utility for each state	Age, stage	Ecological level of societal perspectives Individual-level preferences

^*ER = estrogen receptor; HR = hormone receptor; WWII = World War II.