Breast Density Should Not Be the Only Criterion for Supplemental Breast Cancer Screening
A large prospective study investigating the association between dense breast tissue and the risk for interval breast cancer has found that breast density alone should not be the sole criterion for recommending supplemental breast imaging, because not all women with dense breasts have high interval cancer rates. Incorporating other risk factors, such as age, first-degree relatives with a breast cancer history, history of breast biopsy, BI-RADS breast density, and race/ethnicity, can identify women at high risk for interval cancer who are more likely to benefit from alternative screening strategies. The study by by Kerlikowske et al was published in Annals of Internal Medicine.
Study Methodology
The researchers analyzed screening data from the Breast Cancer Surveillance Consortium (BCSC) on 365,426 women aged 40 to 74 who had 831,455 digital screening mammography examinations performed between January 2002 and October 2011. The women did not have a history of breast cancer or breast implants. Demographic and breast health history information were obtained from a self-administered questionnaire patients completed at each examination.
Radiologists categorized breast density using BI-RADS density categories. Other measures included BCSC 5-year breast cancer risk and interval cancer rate (invasive cancer ≤ 12 months after a normal mammography result) per 1,000 mammography examinations. High interval cancer rate was defined as more than 1 case per 1,000 examinations.
Study Findings
The researchers found that high interval cancer rates were observed for women with 5-year risk ≥ 1.67% and extremely dense breasts or 5-year risk ≥ 2.50% and heterogeneously dense breasts (24% of all women with dense breasts). The interval rate of advanced-stage disease was highest (> 0.4 case per 1,000 examinations) among women with 5-year risk ≥ 2.50% and heterogeneously or extremely dense breasts (21% of all women with dense breasts). Five-year risk was low to average (0% to 1.66%) for 51.0% of women with heterogeneously dense breasts and 52.5% with extremely dense breasts, with interval cancer rates of 0.58 to 0.63.
“We found that not all women with dense breasts are at sufficiently high risk for interval cancer to justify consideration of supplemental or alternative screening methods. Primary care providers can calculate 5-year breast cancer risk using the BCSC risk calculator and use this information in their discussions about supplemental or alternative screening methods in women with dense breasts,” concluded the researchers.
Diana L. Miglioretti, PhD, of UC Davis School of Medicine, is the corresponding author for the Annals of Internal Medicine article.
Primary funding for this study was provided by the National Cancer Institute. For full disclosures of the study authors, visit www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M14-1465.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
