Cancer Risk of Benign Breast Lumps Studied

New research links some non-cancerous breast lumps to a slightly higher risk of breast cancer.

But there are many influences on breast cancer. The vast majority of women won't develop breast cancer as a result of benign breast lumps.

Those findings appear in a study and related editorial in The New England Journal of Medicine.

Read Web MD's "Learn How to do a Breast Self-Exam."

Breast Lumps Are Common

Many women feel lumps in their breasts, especially before their menstrual period.

It can be reassuring to know that most breast lumps aren't cancer. While heart disease actually kills more women — and breast cancer survival is improving — many women fear breast cancer.

Still, it's important to have a doctor check out any breast lumps, get recommended screenings, and learn what's normal for your body.

Mammography, ultrasound, and biopsies are tools doctors may use to identify the type of lump.

Read Web MD's "Learn More About Breast Cancer Screening."

Types of Benign Breast Lumps

Since most breast lumps aren't cancer, what are they?

Here's a quick rundown from the Susan G. Komen Breast Cancer Foundation:

—Cysts: tiny fluid-filled sacs that are almost always benign.

—Fibroadenomas: another type of benign lump.

—Calcifications: scattered or clustered bits of calcium in the breast.

—Hyperplasia: a noncancerous condition in which there is an excess of multiplying cells.

Hyperplasia raises the risk of breast cancer, states the Komen Foundation's web site.

Occasionally, clusters of tiny calcifications (microcalcifications) can indicate cancer or precursors to cancer, the foundation's web site states.

Read Web MD's "What Women Want to Know Before First Mammogram."

Latest Study

Lynn Hartmann, MD, and colleagues studied more than 9,000 women with noncancerous breast lumps.

The women were 18-85 years old. They were diagnosed at the Mayo Clinic in Rochester, Minn., with benign breast disease between 1967 and 1991.

Over about 15 years, the group had 707 breast cancers. That's more than what's typical among women in the general public, writes Hartmann, who works in the Mayo Clinic's medical oncology department.

Family history of breast cancer was important. So was the type of benign breast lump.

Having a family history of breast cancer raised the odds of getting breast cancer. Women without a family history of breast cancer and benign lumps (those not characterized by multiplying cells) were not more likely to get breast cancer.

Read Web MD's "The Breast Cancer Gene: What Should You Do?"

Real-World Numbers

Joann Elmore, MD, MPH, and colleagues, in an editorial in The New England Journal of Medicine, put the numbers in simple terms.

Here are their estimates — based on the study — for the number of women developing breast cancer over an average of 15 years:

—Women in the general population: 5 in 100

—Women with nonspreading benign lumps: 6 in 100

—Increase in absolute risk for women with nonspreading benign lumps: 1 in 100

—Women with atypical hyperplasia: 19 in 100

"The use of relative risk suggests greater effects than truly exist, whereas the use of absolute risks ... prevents this misunderstanding," write Elmore and colleagues.

Doctors should make statistics easy to understand, discuss options, and pay attention to how they talk to patients, they write.

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Glass Half Full or Half Empty?

"Positive framing emphasizes the absence of disease; negative framing emphasizes the presence of disease," they write.

Out of 100 women in the general public, 95 will not develop breast cancer within the next 15 years. The same is true for 94 out of 100 women with nonspreading benign breast lumps, they write.

"People are sensitive to framing," writes Elmore. She works in the medicine department of the University of Washington's medical school.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Hartmann, L. The New England Journal of Medicine, July 21, 2005; vol 353: pp 229-237. Susan G. Komen Foundation: "Breast Facts: What Is Benign Breast Disease?" Elmore, J. The New England Journal of Medicine, July 21, 2005; vol 353: p 297. News release, Mayo Clinic.