Ginger Merry MD, MPH, Presenter: Nothing to Disclose

Diana Miglioretti PhD, Abstract Co-Author: Nothing to Disclose

Choonsik Lee, Abstract Co-Author: Nothing to Disclose

Eric Johnson, Abstract Co-Author: Nothing to Disclose

Rebecca Smith-Bindman MD, Abstract Co-Author: Nothing to Disclose

Utilization of chest and cardiac CT, and cardiac medicine, has grown rapidly over the last 10 years. The impact of this increased use of imaging on radiation exposure to breast tissue and subsequent risk of breast cancer has not been determined

We evaluated imaging and associated radiation exposure among female members enrolled in a large integrated health care system between 2000 and 2010, including over 250,000 enrollees each year. We collected CT dose parameters on 1,656 patients and used a newly developed, automated Monte Carlo computational method to estimate breast and effective doses. For nuclear medicine, data were abstracted on the volume of injected radiopharmaceutical for 5,507 exams and Monte Carlo methods were used to estimate breast doses. The breast-specific absorbed doses and the Preston 2002 pooled model for radiation-effects on breast cancer risk were used to estimate women’s 10 year risk of developing breast cancer based on age at exposure to CT. Using Breast Cancer Surveillance Consortium data, we estimated women’s 10 year risk of breast cancer based on the Gail model and SEER age-specific cancer incidence data and compared the imaging-related risk to the underlying Gail risk.

Overall 124 CTs and 42 nuclear medicine exams were obtained per 1000 female enrollees per year, with rapid increase between 2000 and 2010. Breast doses from CT were variable, with the highest breast doses delivered by multiple-phase cardiac [median 51.6 mGy, IQR 21.2, 73.1] and chest CT [median 34 mGy; IQR 16, 74). A child or young adult who underwent two cardiac or chest CTs before the age of 23 has a higher 10-year risk of developing breast cancer from these exams than her underlying risk of developing breast cancer in the same period (Figure). Thus a child or young adult who undergoes two or more chest or cardiac CTs more than doubles her 10-year risk of breast cancer.

Women should understand there is a small but real potential risk of breast cancer associated with cardiac and chest CT, and the risk increases with the number of scans.

Cardiac and Chest CT deliver significant doses of radiation to the breast in children and young adults and repeated imaging can more than double a woman's 10 year risk of breat cancer.

Merry, G, Miglioretti, D, Lee, C, Johnson, E, Smith-Bindman, R, Breast Cancer Risks from Medical Imaging Including Computed Tomography (CT) and Nuclear Medicine among Females Enrolled in a Large Integrated Health Care System.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12035878.html