(ChemotherapyAdvisor) – Women ages 50 years and older who have mammographic density ≥25% had a significantly higher risk of breast cancer recurrence, nearly twice that of women with a density <25%, investigators from the Karolinska Institutet in Stockholm, Sweden, reported on March 21 during the 8th European Breast Cancer Conference in Vienna, Austria.

Although mammographic density is a well-established risk factor for breast cancer, little is known about the association between density, tumor characteristics, and prognosis, Louise Eriksson and colleagues reported.

In this study, one of the largest to date, they included postmenopausal women from a population-based case-control study of women ages 50 to 74 years with incident breast cancer diagnosed between 1993 and 1995 for whom mammograms were available (n=1,774).

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Mammographic density was assessed using a computer-assisted thresholding technique. Percentage mammographic density was positively associated with tumor size (P=0.004) and grade (P=0.033); however, grade was attenuated after adjustment for mode of detection (P=0.069). After adjustment for treatment, percentage mammographic density was associated with both breast and locoregional recurrence; in addition to an HR of 1.96 for breast recurrence (P=0.032), HR was 1.78 for locoregional recurrence (P=0.017).

No other associations between percentage mammographic density and tumor characteristics studied were observed, including hormone receptor status, lymph node metastasis, proliferation rate, and histopathological classification; density did not increase risk of distant metastasis and had no effect on survival.

“Density may be viewed as fertile soil, increasing both risk of primary breast cancer, independent of subtype, and risk of recurrence,” the investigators concluded. “Thus, density should not only be taken into consideration in the screening setting, but also when making decisions on adjuvant therapy and follow-up regimes.”

Abstract (Enter “Eriksson” in author box to search for Abstract #102)