According to a new study, women diagnosed with a form of benign breast disease, but who do not have a strong family history of breast cancer, have no heightened risk of developing a tumor.
Lynn Hartmann, chief author of the report, an oncologist at the Mayo Clinic, says as far as she is concerned this comes under the 'good news' category.
Apparently doctors have long known that changes in the breast are often a predictor of cancer, and Hartmann in her study looked at 9,087 women with benign breast disease over an average period of 15 years, in order to quantify those risks.
The researchers found that among women with cysts, also known as non-proliferation disease, the breast cancer risk was 27 percent higher than expected.
This was the most common type of benign disease found in 67 percent of the women in the study, and 1 million women in the United States are diagnosed with such disease every year.
It was found that for every 100 women with non-proliferation disease, about six develop breast cancer, compared with five cases in 100 expected over the 15-year period among women in the general population.
A cyst occurs when a breast duct becomes enlarged and filled with fluid, and the tissue around the duct thickens because it contains too much collagen.
In cases of atypical hyperplasia, where cells of the breast look too large, too abundant and abnormal under the microscope, but not abnormal enough to be cancerous, the risk of breast cancer quadruples, and in that case, 19 out of 100 of those women are likely to develop a tumor over the next 15 years.
However only 4 percent of women with some type of benign breast disease fall into that category.
Hartmann says that earlier estimates set the risk much higher, possibly eight to 10 times higher among women with a family history of breast cancer. She says they did not see that.
Those women who fall into this category, especially younger women, may be candidates for taking drugs like tamoxifen, which is designed to prevent breast cancer, or having their breasts checked using MRIs instead of conventional mammography.
In the intermediate cases, which represented about 30 percent of the women in the study, the cells appear to be growing a little too rapidly, but still look normal.
It was found that among those women, the risk of breast cancer was twice what would normally be expected, or 10 women out of 100 during the 15-year period.
Age also plays an important role in the risk factor, and women diagnosed with atypical hyperplasia, under the age of 45, face twice the risk of cancer than women found to have hyperplasia at age 56 and over.
The study is published in the current edition of the New England Journal of Medicine.