A new study presents what may be a more accurate model for predicting breast cancer in
women diagnosed with a condition that often presages that malignancy. The finding is good news for doctors seeking to develop
risk-reduction strategies for the condition, called atypical hyperplasia
Hyperplasias
are benign, microscopic clusters of cells usually found through sampling of breast tissue. If the growth is abnormal, the
resulting atypical hyperplasia can increase a woman's risk of breast cancer. Researchers at the Mayo Clinic studied 331 women
diagnosed with atypia for an average of about 14 years, noting the number of foci, or spots, of the aberrant cell growths
in each participant and how many women actually developed breast cancer. They found that the risk of developing the cancer
varied depending on the number of foci of atypia. One focus more than doubled the
risk for women compared with the general population, while the risk increased five-fold with the presence of two foci, and
nearly eight-fold for three or more.
The
study, published in the July 1, 07, edition of the Journal of Oncology, calls into question how the system called the
Gail model, which is widely used to assess breast cancer risk prediction, should be applied to women with atypia. The Gail
model weighs family history of breast cancer in calculating lifetime risk for the disease. The Mayo study found that, for
women with atypical hyperplasia, the cancer risk was independent of family history. That inconsistency suggests the Gail model
overestimates risk for women who have both atypia and a family history of breast cancer.
This
new understanding of risk prediction may also stretch out the time frame during which women need to be concerned. "Previous
studies indicated that there was an increased risk for breast cancer for only 10 years after a biopsy showed the presence
of atypia," says Amy Degnim, the study's lead author and an assistant professor of surgery at the Mayo Clinic. "That's not
what we found. The increased risk persisted up to 25 years." The researchers also found that women diagnosed with atypia before
the age of 45 had a higher risk of developing breast cancer than those diagnosed after age 55.
While
the findings can't yet be translated into clinical practice, Degnim is confident that assessing breast cancer risk from the
number of atypia foci will offer women more accurate risk estimates and eventually improve their care. Armed with a more reliable
measurement of the risk facing each patient, doctors will be better able to "advise patients on preventive strategies, including
close surveillance with mammography, hormonal treatments with tamoxifen or raloxifene, and lifestyle changes like limiting
alcohol intake and maintaining healthy body weight," according to Ted Gansler, a pathologist and director of clinical content
for the American Cancer Society.
