had an enrollment goal of 100,000. Study components and primary findings The WHI study was composed of four study components, to include three overlapping clinical trial (CT) interventions and one observational study (OS). Component enrollment and the primary findings are summarized in the following two tables, respectively, with additional detail following subsequently: Hormone therapy The design of the hormone therapy trial (HT) was approached with the hypothesis that estrogen therapy would result in a decrease in coronary heart disease and osteoporosis-related fractures. As such, the primary outcome of interest was coronary heart disease, as this is a major cause of morbidity and mortality among women, particularly those over age 65, and because, at the time, no clinical trial had been undertaken to prove the cardioprotective effects of HT. Due to the concern over the relationship between HT and elevated breast cancer risk, breast cancer was selected as the primary adverse outcome. Additional outcomes monitored included stroke, pulmonary embolism (PE), endometrial cancer, colorectal cancer, hip fracture, and death due to other causes. Two regimens were selected, in addition to a placebo group. Women assigned to the intervention group who had previously undergone a hysterectomy were treated with unopposed estrogen, specifically conjugated estrogens (Premarin, manufactured by Wyeth), at a dosage of 0.625 mg/day ("E-alone," n = 5310; placebo, n = 5429). Women with an intact uterus were treated by a combined estrogen plus progestin regimen ("E+P," n = 8506; placebo, n = 8102), specifically the aforementioned estrogen regimen with the addition of 2.5 mg/day of medroxyprogesterone acetate (MPA; Prempro, also manufactured by Wyeth). The addition of progestin has been linked to a marked reduction in the risk for the development of endometrial cancer in women receiving estrogen treatment who have not undergone a hysterectomy. In addition to the global exclusion criteria, women were ineligible for the HT component if safety was a concern. Such concerns included a breast cancer diagnosis at any time in the past, other cancers (excluding non-melanoma skin cancer) diagnosed within the previous 10 years, or low hematocrit or platelet counts. HT component findings and ensuing events The HT component had originally been designed to include a follow-up period of nine years. However, interim monitoring of the combined estrogen/progestin treatment group indicated an increased risk of breast cancer, coronary heart disease, stroke, and pulmonary embolism, which outweighed the evidence indicating a benefit in preventing colorectal cancer and fractures. As