SAN ANTONIO — All women with atypical hyperplasia in a benign breast biopsy are at significantly increased risk of developing breast cancer, but the magnitude of risk is greater when the pathology involves atypical lobular hyperplasia than it is with atypical ductal hyperplasia, according to data from the Nurses' Health Study.
Only about 60% of the breast cancers that develop in women with either atypical lobular hyperplasia or atypical ductal hyperplasia occur in the ipsilateral breast. For this reason, both types of atypical hyperplasia are best regarded for purposes of clinical management as markers of a generalized bilateral increase in breast cancer risk, Dr. Laura C. Collins said at a breast cancer symposium sponsored by the Cancer Therapy and Research Center.
She reported on 2,016 participants in the Nurses' Health Study who had a benign breast biopsy; 395 of them subsequently developed breast cancer. The 1,621 controls were matched to the cancer patients by age and year of their benign breast biopsy.
Of the women with atypical hyperplasia in a benign breast biopsy, 75 went on to develop breast cancer. That translated into an adjusted 3.93-fold greater risk of developing the malignancy for women with atypical hyperplasia compared with those who had a benign breast biopsy showing only nonproliferative changes, said Dr. Collins, a pathologist at Beth Israel Deaconess Medical Center and Harvard Medical School, Boston.
The adjusted odds ratio for developing breast cancer was 2.76 for women with atypical ductal hyperplasia, 5.24 for those with atypical lobular hyperplasia, and 8.12 for women with both histologic abnormalities.
The risk of developing breast cancer was roughly twice as great 10 years or longer following a benign biopsy featuring atypical ductal hyperplasia as in the first 10 years of follow-up. In contrast, breast cancer risk in women with atypical lobular hyperplasia remained steady over time.
Atypical lobular and atypical ductal hyperplasia also differed in terms of the impact menopausal status at the time of the benign breast biopsy had on subsequent breast cancer risk. Women who were premenopausal at the time of a benign breast biopsy showing atypical lobular hyperplasia had a 6.67-fold increased breast cancer risk. Women who were postmenopausal at the time of biopsy had a 3.41-fold increased risk.
In contrast, patients who were premenopausal when they had a breast biopsy showing atypical ductal hyperplasia had a 2.59-fold increased risk of subsequent breast cancer, whereas those who were postmenopausal at the time of their benign biopsy had a 4.04-fold increased breast cancer risk, Dr. Collins noted.
The Nurses' Health Study is an ongoing prospective study involving U.S. registered nurses aged 25–55 years at entry. At present, more than 237,000 women are enrolled.
The adjusted odds ratio for developing breast cancer was 5.24 for those with atypical lobular hyperplasia. DR. COLLINS