Post-diagnosis mammographic density and risk of death in breast cancer survivors: The Health, Eating, Activity, and Lifestyle (HEAL) study

Abstract

22095 Background: There is evidence that mammographic breast density (BD) is a strong risk factor for breast cancer; however, no study has examined the association between BD and death in breast cancer survivors. We examined the association between post- diagnosis BD and risk of all causes of death and breast cancer death in breast cancer survivors. Methods: Prospective observational study of 524 women enrolled in the Health, Eating, Activity, and Lifestyle (HEAL) Study who were diagnosed with breast cancer between 1995 and 1998 and followed until death or September 2004. We collected a mammogram and prognostic, demographic, and lifestyle factors including measured weight and height during a clinic visit two to three years after diagnosis. Mammograms were digitized and the cranio-caudal view contralateral to the breast diagnosed with breast cancer was measured for percent density and dense area using a computer-assisted program developed at University of Toronto. Results: The age and BMI of women were 58.3 ± 10.6 yrs and 27.7 ± 6.7 kg/m2. Women were postmenopausal (81%); non-Hispanic White (59%), African American (25%) or Hispanic White (13%); and diagnosed with Stage I (72%) or Stage II (28%) breast cancer. Seventy-one % of women were diagnosed with tumors that were estrogen receptor-positive. In analyses adjusted for age, menopausal status, race, disease stage, hormone therapy, BMI, physical activity, smoking status, and family history of breast cancer, the adjusted hazard ratio (HR) and 95% confidence interval (CI) for women in the highest vs. the lowest tertile of amount of dense tissue and all causes of death was 2.47 (95% CI, 1.01–6.23), P for trend = 0.049. Similar, yet nonsignificant associations, were observed for amount of dense tissue and breast cancer deaths. The adjusted HR for women in the highest vs. the lowest tertile of percent dense tissue and all causes of death was 1.38 (95% CI, 0.57–3.31), P for trend = 0.48. Similar nonsignificant associations were observed between percent dense tissue and breast cancer deaths. Conclusions: Women with high amounts of dense tissue were at a 2.5 times greater risk of death compared to women with lower amounts of dense tissue. Increased BD may be a marker of tumor aggressiveness or response to therapy. No significant financial relationships to disclose.