(HealthDay News) – Atypical ductal hyperplasia (ADH) and atypical lobular hyperplasia (ALH) exhibit similar behavior in terms of later breast cancer end points, according to a study published online January 30 in Cancer Prevention Research.

Lynn C. Hartmann, MD, from the Mayo Clinic in Rochester, MN, and colleagues studied the characteristics of the breast cancers that develop in women with ADH and ALH to test the assumptions that ADH is a direct precursor for low-grade ductal breast cancer and that ALH serves as a risk indicator. A total of 698 women with ADH or ALH from 1967–2001 were identified from the Mayo Benign Breast Disease Cohort and followed for later breast cancers.

During a mean follow-up of 12.5 years, the researchers found that 143 women developed breast cancer. There was a 2:1 ratio of ipsilateral to contralateral breast cancer for both ADH and ALH, with marked ipsilateral predominance in the first five years, indicative of a precursor phenotype. Invasive ductal cancers were predominant for both ADH and ALH, with 69% moderate or high grade. Twenty-five percent of cancers were node positive. ADH and ALH portended risk for ductal carcinoma in situ and invasive breast cancers, mainly ductal, of which two-thirds were moderate or high grade. In the first five years after atypia, the ipsilateral breast was at especially high risk for breast cancer, with long-term elevated risk in both breasts.

“In summary, these findings underscore the importance of both ADH and ALH as premalignant lesions arising in an altered tissue bed,” the authors write. “These longitudinal data can help to inform clinical management strategies.”

One author disclosed financial ties to Pfizer.

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