Does Mammography Result in Overtreatment?

From the WebMD Archives

June 21, 2000 -- Although the majority of women in the U.S. appear to understand the importance of getting regular mammograms to detect breast cancer early, most don't know enough about the common abnormalities that mammograms can detect to make informed treatment decisions -- and their doctors should be telling them more about them, a survey suggests.

The most common type of breast abnormality detected by mammography is ductal carcinoma in situ (DCIS), a precancerous lesion that is confined to the milk ducts of the breast. Many women with DCIS will never develop cancer in their lifetime; others will, but doctors don't really know how to predict when cancer might occur and in whom. Therefore, the management and treatment of DCIS can be controversial.

Typically, when mammography shows a DCIS-like abnormality, physicians will do a biopsy to examine the lesion and confirm a diagnosis. Some doctors and patients will choose the "watch and wait" method -- checking the lesion every six months with mammography to see if it is progressing. But others will consider aggressive treatment that may include surgery, drug treatment with tamoxifen, or radiation.

In the June 17 issue of the British Medical Journal, researchers suggest that if only a small proportion of DCIS lesions ever progress to cancer, it raises questions about the possibility that many women will be overtreated, since mammography has such a high probability of detecting abnormalities. Co-author Steven Woloshin, MD, says the survey of 479 women that he and colleagues conducted suggests that most women don't know enough about DCIS to make informed decisions and that their doctors should be telling them more about it.

"It's a very difficult dilemma, and the issue is that, in our effort to find all cancers, inevitably we will pick up things in the 'gray' zone. For some of these people, we don't know if we are doing more harm than good," says Woloshin, who is assistant professor of medicine at the VA Medical Center in White River Junction, Vt.

But Anne Blackwood, MD, who reviewed the survey results for WebMD, says while it is important for women to have knowledge of DCIS and other abnormalities that can be detected on mammograms, she says fear of the mammogram detecting something should not deter women from getting their mammograms on time. Having a discussion about DCIS -- what it means and how it's treated -- is something that usually happens after a diagnosis is made, she says.


"Breast cancer is clearly an illness, and ductal carcinoma in situ is a lesion that directly precedes invasive breast cancer," says Blackwood, who is an assistant professor of medicine and epidemiology at the University of Pennsylvania Cancer Center in Philadelphia. "If we can eradicate ductal carcinoma in situ, the potential for an invasive breast cancer to develop from that lesion doesn't exist."

Woloshin's survey also found that the vast majority of women are aware that mammography can sometimes indicate an abnormality that isn't actually there, commonly referred to as a false-positive result. False-positive results can cause unnecessary anxiety, testing, and occasionally treatment, but most women surveyed said they felt such results are an acceptable part of the screening process.

The women also were asked about the safety of mammography and the perceived benefit. Overall, 92% of women thought mammography was safe, and 94% believed that women whose cancer was diagnosed by mammography benefited from being screened. Most women also believed mammography reduced the chance of dying from breast cancer, although none thought mammography reduced the risk to zero.

The American Cancer Society recommends yearly mammograms for all women 40 years of age and older. Along with having mammograms, women should also perform monthly breast self-exams, and those 40 years of age and older should receive an exam of the breast and underarm by a health care professional each year. Any unusual nipple discharge, mass, tenderness, or dimpling of the skin should be reported to a physician immediately.

Vital Information:

  • Women may understand the importance of receiving regular mammograms, but they may not know about common abnormalities that may be detected.
  • One such abnormality is ductal carcinoma in situ (DCIS), which is a precancerous lesion that may or may not progress to breast cancer, but there isn't a consensus on how this should be managed.
  • Another common occurrence is when mammography picks up an abnormality that isn't really there, known as a false-positive.
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