Breast J. 2020;00:1–4. wileyonlinelibrary.com/journal/tbj | 1 © 2020 Wiley Periodicals LLC 1 | INTRODUCTION Breast cancer remains the second leading cause of cancer deaths among women. The American Cancer Society estimates that 276 480 cases of invasive breast cancer will be diagnosed in women in the United States in 2020, and of these, 42 170 women are ex- pected to die from the disease. 1 Breast cancer prevention using risk assessment tools and risk reduction strategies is evolving with the availability of medical and surgical interventions to reduce a woman's risk of cancer. 2-5 Atypical hyperplasia (AH), including atypical lobular hyperplasia (ALH) and atypical ductal hyperplasia (ADH), and lobular carcinoma in situ (LCIS) are markers for an increased risk of breast cancer. The diag- nosis of AH and/or LCIS offers an opportunity for breast cancer pre- vention, using appropriate risk reduction strategies and increased surveillance. This study documents the incidence of these breast cancer risk markers and subsequent breast cancer development over a time period approaching 20 years in one institution. 2 | METHODS 2.1 | Data collection The data from all mammographic procedures performed from January 1997 through December 2006 at the Hoffman Breast Center at Mount Auburn Hospital in Cambridge, MA, were retro- spectively analyzed and entered into a longitudinal data bank fol- lowing approval by the Institutional Review Board. A total of 5734 breast biopsies were performed due to the detection of radiologic abnormalities. All of the cases included underwent surgical excision. Biopsy results for AH, LCIS, ductal carcinoma in situ (DCIS), and inva- sive carcinoma were tabulated. Patients were categorized according to the primary diagnosis. As an example, a patient with invasive carci- noma and LCIS was categorized as having invasive carcinoma. If a pa- tient had two biopsies of the same breast within a short time frame, the patient was recorded only once. If the diagnosis changed after excisional biopsy, only the final diagnosis was included. Patients with Received: 25 June 2020 | Revised: 1 October 2020 | Accepted: 2 October 2020 DOI: 10.1111/tbj.14097 SHORT COMMUNICATION Longitudinal study of breast cancer risk markers Corrine Zarwan MD 1,2 | Olivia Diamond MD 3,4 | Prudence Lam MD 3,4 | Musie S. Ghebremichael PhD 5 | Margaret Lotz PhD 3 | Abra H. Shen SB 6 | Sheida Sharifi MD 1,2 | Flora Rozhansky MD 7 | Teresa Ann Gore ANP-BC 8 | Susan E. Pories MD 3,4 1 Lahey Hospital and Medical Center, Burlington, MA, USA 2 Tufts School of Medicine, Boston, MA, USA 3 Mount Auburn Hospital, Cambridge, MA, USA 4 Harvard Medical School, Boston, MA, USA 5 Harvard School of Public Health and Ragon Institute, Cambridge, MA, USA 6 HMS IV, Harvard Medical School, Boston, MA, USA 7 Spaulding Rehabilitation Hospital, Cambridge, MA, USA 8 Merrimack Valley Internal Medicine Associates, North Chelmsford, MA, USA Correspondence Dr Susan E. Pories, Mount Auburn Hospital, 300 Mount Auburn Street, Medical Office Building, Suite 313, Cambridge, MA 02138, USA. Email: spories@mah.harvard.edu Abstract Atypical hyperplasia (AH) and lobular carcinoma in situ (LCIS) are markers for an in- creased risk of breast cancer, yet outcomes for these diagnoses are not well-docu- mented. In this study, all breast biopsies performed for radiologic abnormalities over a 10-year period were reviewed. Patients with AH or LCIS were followed for an ad- ditional 10 years to assess subsequent rates of cancer diagnosis. Long-term follow-up showed that 25 (7.8%) patients with AH and 5 patients with LCIS (5.7%) developed breast cancer over the follow-up period, a lower rate of breast cancer development than predicted by risk models. KEYWORDS atypical ductal hyperplasia, atypical hyperplasia, atypical lobular hyperplasia, breast cancer, lobular carcinoma in situ, risk