Certain Types of Non-cancerous Breast Lumps Are Associated with a Higher Risk of Breast Cancer
L. Hartmann et al.,
New England Journal of Medicine, July 21, 2005
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August 2005 Research News
Inflammatory Breast Cancer, Though Rare, Is Being Diagnosed More Often
Certain Types of Non-cancerous Breast Lumps Are Associated with a Higher Risk of Breast Cancer
Is this for me? If you've had a benign (not cancerous) breast lump, this article can help you find out whether that affects your risk of developing breast cancer.
Background and importance of the study: Eight out of 10 lumps that women (or their health care providers) feel in their breasts turn out to be benign (not cancerous). A benign lump is a group of breast cells that might appear normal or somewhat abnormal, and the cells might be growing at a normal rate or faster than normal (hyperactive).
After getting a breast biopsy and waiting for the results, finding out that a lump is benign comes as a HUGE relief. But some benign breast lumps can increase your risk for developing breast cancer later. Studies have shown that women who have benign breast lumps are 50–60% more likely than other women to develop breast cancer.
Not all benign breast lumps are the same, though. It's unclear whether all types of benign lumps influence breast cancer risk in the same way.
In the study reviewed here, researchers looked at a large number of women who were diagnosed with benign breast lumps. The researchers wanted to see how many of the women later developed breast cancer and whether a certain type of benign breast lump was associated with a higher risk of developing breast cancer.
Study design: Researchers from four institutions looked at information on 9,087 women who had surgery to remove a benign breast lump at the Mayo Clinic between 1967 and 1991. The women were between 18 and 85 years old. The study was funded by the U.S. Department of Defense, the National Institutes of Health, the Susan G. Komen Breast Cancer Foundation, the Breast Cancer Research Foundation, and the Andersen Foundation.
The researchers sent each woman a questionnaire asking about
:
- her family history of breast cancer,
- her age and menopausal status when she had the surgery, and
- whether she had ever been diagnosed with breast cancer.
The researchers also looked at the women's medical records after surgery to add to the information they received from the questionnaires.
Next, a breast pathologist used a microscope to look at tissue samples from the benign lumps that had been removed from each woman in the study. The pathologist classified each lump into one of three categories:
- non-proliferative changes—fibrous tissue, which forms ligaments or tendons, or fluid-filled cysts, with cells that are growing at a normal rate.
- proliferative changes—cells grow and make new cells more rapidly than normal—without atypia—the cells appear normal.
- proliferative changes—cells grow and make new cells more rapidly than normal—with atypia—cells start to look different from normal cells. In atypical ductal hyperplasia, the abnormal cells are in the milk duct. In atypical lobular hyperplasia, the abnormal cells are in the milk-making glands. Atypical hyperplasia is also used to describe either category.
To find out which kinds of breast lumps are and are not associated with an increased risk of breast cancer, the researchers followed the women for many years after their benign breast lumps were removed. Most of the women were followed for about 15 years.
To judge whether having a benign breast lump increases the risk of getting breast cancer, the researchers needed to know how many women would be estimated to get breast cancer in an AVERAGE population. The researchers used the Surveillance, Epidemiology, and End Results (SEER) registry, a huge collection of information on how many people get cancer each year (incidence) and how long they live (survival). The National Cancer Institute manages this registry.
Results: During the follow-up period, 707 of the 9,087 women who were followed in this study were diagnosed with breast cancer. By comparison, based on the SEER registry, the researchers estimated that 453 out of 9,087 women in the general population (without a known history of a benign breast lump) would be diagnosed with breast cancer during that same period. This means that a diagnosis of benign breast disease increased the risk of later getting breast cancer by about 56%. The increase in risk could be seen for up to 25 years after the initial surgery to remove the benign breast lump.
The benign breast lumps of the 9,087 women in the study were classified as follows:
- 66.7% (in 6,061 women) were non-proliferative changes.
- 29.6% (in 2,690 women) were proliferative changes without atypia.
- 3.7% (in 336 women) were proliferative changes with atypia (atypical hyperplasia).
The researchers found that the TYPE of benign breast disease was an important predictor of breast cancer risk. Compared to the average SEER population (women without any known history of cancer or benign breast lumps), women in this study:
- with atypical hyperplasia were 424% more likely to develop breast cancer (more than four times the average woman's risk).
- with proliferative changes without atypia were 88% more likely to develop breast cancer.
- with non-proliferative changes were 27% more likely to develop breast cancer.
Family history of breast cancer also influenced the women's risk of developing the disease. Compared to the average population:
- women with a strong family history (one first-degree relative with breast cancer before age 50, or two or more relatives, at least one of them first-degree, with breast cancer) were 93% more likely to develop breast cancer. A first-degree relative is a mother, sister, or daughter.
- women with a weak family history (any family history of breast cancer not defined as strong above) were 43% more likely to develop breast cancer.
- women with no family history of breast cancer were 18% more likely to develop breast cancer.
However, family history information was available for only about half (53%) of the women in the study.
The researchers also looked at the average age of women who had a benign breast lump. For all of the women in the study, the average age at surgery was about 51. But women with non-proliferative lumps were slightly younger (about 50) than the whole group. And women with atypical hyperplasia were slightly older (about 58).
The researchers then looked for any relationships between the different breast cancer risk factors. They found that for women diagnosed with atypical hyperplasia, the age at diagnosis made a difference. When compared to the average woman in the SEER registry:
- Women younger than 45 with atypical hyperplasia were seven times more likely to develop breast cancer.
- Women between 45 and 55 with atypical hyperplasia were five times more likely to develop breast cancer.
- Women older than 55 with atypical hyperplasia were three times more likely to develop breast cancer.
It's important to note that, for women with non-proliferative breast lumps who had a weak or no family history of breast cancer, there was NO increase in the risk of breast cancer.
Conclusions: The researchers concluded that certain types of benign breast disease can increase the risk of breast cancer. The researchers also concluded that family history and age at diagnosis may further influence this risk.
- Women with atypical hyperplasia were 424% (four times) more likely to develop breast cancer than the average woman without a history of a benign breast lump. To put this in perspective, let's look at the absolute risk of the women (the numbers here are rounded to make it easier to understand). The average woman's risk is 5 out of 100; for women with atypical hyperplasia, about 20 out of 100 women will develop breast cancer.
- Women with proliferative changes without hyperplasia were 88% more likely to develop breast cancer. In terms of absolute risk, this means that about 10 out of 100 will develop breast cancer.
- Women with non-proliferative lumps were 27% more likely to develop breast cancer. In terms of absolute risk, this means that 6 out of 100 will develop breast cancer.
Women younger than 45 who were diagnosed with atypical hyperplasia had the greatest increased risk. They were seven times more likely than an average woman to develop breast cancer.
Women with non-proliferative lumps who had a weak or no family history of breast cancer had NO increase in breast cancer risk.
In this study, the benign tumors were classified as follows:
- 66.7% (in 6,061 women) were non-proliferative changes.
- 29.6% (in 2,690 women) were proliferative changes without atypia.
- 3.7% (in 336 women) were proliferative changes with atypia—atypical hyperplasia.
This means that only 3.7% of the women had the highest risk of developing breast cancer. And almost 67% had the lowest risk of developing breast cancer.
Take-home message: Out of 10 women who find lumps in their breasts, eight of them will receive a diagnosis of a benign lump. If you're one of these eight women, you're totally relieved and thankful. Your conversation with your doctor is probably short and upbeat.
But this research suggests that the answer of "no cancer" shouldn't end your discussion with your doctor. This study might be able to help you and your doctor learn as much as you can about how to take care of you in the future. Because the study is big, with careful pathology review and 15 years of follow-up, the results are reliable and give us a better idea of how the changes that produce breast lumps may influence your risk of developing breast cancer.
If your pathology report says you have a benign lump, that's terrific! But you need to know more. What TYPE of benign lump do you have? Are the cells proliferative—growing rapidly? Are the cells atypical—do they look abnormal in some way?
Not all breast pathologists use the same terms in the same ways to describe the different types of breast cells. There are a lot of steps between normal cells and cancer cells, and some of these changes may be small and subtle. So two pathologists may classify a group of cells in two different ways. And a pathologist may use another term instead of proliferation, such as hyperplasia or increased mitosis. Ask your doctor for a copy of your pathology report. If there are any terms you do not understand, ask your doctor for an explanation.
Once you and your doctor both are comfortable with the way your benign lump has been classified, review any history of breast cancer in your family and your age when the lump was found. By looking at all these factors, you'll have a better idea of your risk for developing breast cancer.
Most women who get benign results from their biopsies don't have to be concerned. In this study, almost 67% of the women had non-proliferative lumps with no atypia—the cells looked normal and weren't growing rapidly. And for women with non-proliferative lumps AND no or a weak family history of breast cancer, there was NO INCREASE in risk.
About 30% had proliferative changes with no atypia—the cells were growing, but appeared normal. Only 4% had atypical hyperplasia, which is associated with the highest risk of developing breast cancer.
If your pathology report says that you have atypical hyperplasia and you are younger than 45, or you have a strong family history of breast cancer, you have an increased risk of developing breast cancer in the future.
Lifestyle changes,
medicines, and
surgery are all options that can reduce your risk. Talk to your doctor about these choices and see if any of them make sense for you. And keep visiting breastcancer.org for the latest information on how to reduce your risk for breast cancer.
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