Study Examines Relationship Between Breast Density and Second Breast Cancers for Women with Ductal Carcinoma In Situ (10.05.04)

Oakland, Calif., October 5, 2004--Having highly dense breasts may be associated with an increased risk of a second breast cancer among women who have had a ductal carcinoma in situ (DCIS), according to a study in the October 6^th issue of the Journal of the National Cancer Institute. Conducted by researchers from Kaiser Permanente’s Division of Research, Northern California, and from the National Surgical Adjuvant Breast and Bowel Project (NSABP), this is the first study to examine the potential connection between highly dense breasts and risk of second breast cancer after DCIS.

Women with DCIS--a noninvasive cancer in which malignant-appearing cells are contained within the breast duct--have a substantially increased risk of a second breast cancer, but few predictors of this risk have been identified. Having extensive areas of breast tissue that appear dense on mammograms has been associated with a four- to six-fold greater risk of a first primary breast cancer compared with women who have small or no areas of dense breast tissue.

To see if breast density was related to the risk of getting a second breast cancer after DCIS, Laurel A. Habel, Ph.D., of Kaiser Permanente’s Division of Research in Oakland, Calif., and colleagues studied 504 women (mostly 50 years or older) from the NSABP B-17 trial who had DCIS. The researchers examined the mammograms taken when the women were diagnosed with DCIS and then calculated the risk of subsequent breast cancer events.

While only approximately 7% of women studied had highly dense breasts--75% or more of their breasts composed of dense tissue--this group had 2.8 times the risk of subsequent breast cancer (DCIS or invasive) compared with women who had the least dense breasts (less than 25% of their breasts composed of dense tissue). This increase in risk also was seen when second breast cancer events were restricted to invasive disease or when restricted to ipsilateral breast cancer (cancer in the same breast as the initial DCIS).

The authors suggest that breast density may reflect the activity of hormones and other growth factors. In addition, breast density may affect the accuracy of disease surveillance through mammography and clinical breast examination after treatment for DCIS. Additional studies will be needed to confirm these findings and determine whether measures of breast density might aid in assessment of risk of a second breast cancer after DCIS. Dr. Habel is currently working on a second study to examine this potential link.

|Kaiser Permanente has research centers in 8 regions around the United States and publication of KP investigators’ work has appeared in the Journal of the American Medical Association, the New England Journal of Medicine, Pediatrics, the American Journal of Preventive Medicine, and other peer-reviewed medical journals

Kaiser Permanente is America’s leading integrated health plan. Founded in 1945, it is a not-for-profit, group practice prepayment program with headquarters in Oakland, California. Kaiser Permanente serves the health care needs of over 8.2 million members in 9 states and the District of Columbia. Today it encompasses the not-for-profit Kaiser Foundation Health Plan, Inc., Kaiser Foundation Hospitals and their subsidiaries, and the for-profit Permanente Medical Groups, as well as an affiliation with Group Health Cooperative based in Seattle. Nationwide, Kaiser Permanente includes approximately 136,000 technical, administrative and clerical employees and over 11,000 physicians representing all specialties.

Dr. Habel is available for interviews.

Mammographic Density and Breast Cancer After Ductal Carcinoma In Situ, Laurel A. Habel, James J. Dignam, Stephanie R. Land, Martine Salane, Angela M. Capra, Thomas B. Julian Journal of the National Cancer Institute, Vol. 96, No. 19, October 6, 2004

CONTACTS:
Alexandra Matisoff-Li
Kaiser Permanente Media Relations
(510) 271-5624

Alison Truman
Kaiser Permanente Division of Research
(510) 891-3543

Maureen.McInaney@kp.org