Estimated risk of invasive breast cancer in postmenopausal women with and without family history of the disease

Abstract

To characterize the estimated risk of invasive breast cancer (IBC) in postmenopausal women without a family history of breast cancer (FHBC), baseline risk scores were calculated using the Breast Cancer Risk Assessment tool. We also analyzed the incidence rates of IBC stratified by FHBC. For the Continuing Outcomes Relevant to Evista (CORE) study population (n = 3,991; excluding women ≥86 y of age or with a history of ductal carcinoma in situ or lobular carcinoma in situ), the prevalence of risk factors to the overall IBC risk was calculated. To evaluate IBC incidence rates, the placebo arm of the CORE trial (n = 1,275) was pooled with the placebo arm of the Raloxifene Use for the Heart trial (n = 5,047; total of 6,322 women). Common risk factors in the CORE population were age 65 years or older (78.4%) and menarche at 12 years or younger (29.4%). Incidence rates of IBC in the CORE plus Raloxifene Use for the Heart trial placebo populations correlated with IBC risk estimates; incidence rates were higher as risk scores increased. Of those who developed IBC, 65% (60/92) had scores between 1% and 2% and did not have FHBC; nearly half (43%; 40/92) had risk scores below the high-risk cutoff of 1.66%. A significant portion of women who develop IBC do not have a family history of the disease. FHBC is important in assessing IBC risk; however, other relevant risk factors, together with FHBC and results from a validated tool risk assessment tool, should be jointly considered to develop a complete assessment of women's IBC risk.