About the Condition
The breast is comprised of 2 main types of tissue — glandular and supportive. The glandular portion includes the lobules, which produce milk in women who are breastfeeding, and the ducts, which carry milk from the lobules to the nipple. The supportive portion includes the fibrous connective tissue and fatty tissue that determine the size and shape of the breast. Any of the tissues of the breast can experience symptom-causing changes, which may be either benign or cancerous.
Atypical ductal hyperplasia occurs when there is an overgrowth of cells that line the breast ducts, with the cells looking abnormal when examined microscopically. Although ADH is not cancer, it is a marker for a generalized increase in breast cancer. A similar condition to ADH is atypical lobular hyperplasia, or ALH, which occurs when there is an overgrowth of cells lining the breast lobules.
About 20% of women who have ADH or ALH develop breast cancer within 15 years of their biopsies, with the risk for cancer declining after 15 years. In women who do not have ADH or ALH, about 5% would be expected to develop breast cancer within the same 15-year period. Thus the average overall risk for women with ADH or ALH is about 4 times greater than for other women.
When studied as individual groups, women with ADH have nearly 3 times the risk of developing breast cancer and women with ALH have more than 5 times the risk, or nearly twice as high. Some women have both ADH and ALH, which increases the risk by about 8 times.
Some studies have also shown that the risk of developing breast cancer for women with ADH or ALH lessons with a higher age at the time of diagnosis, with those under 45 at the highest risk, those ages 45 to 55 at a lesser risk and those over 55 at the least risk.
Although ADH is often present in only one breast, it does not mean that any cancer which may later develop will occur in the same breast. In more than a third of cases, cancer develops in the opposite breast.
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