Second pathology opinion for mammography-detected breast cancer

“Screening causes cancer.” When British surgeon and screening critic Michael Baum, MD, once expressed this opinion during a protracted media controversy over the safety of mammograms, it, no doubt, struck many as hyperbole. A recent study of mammography screening in Norway and Sweden, however, shows the comment to have a strong element of truth.

These two Scandinavian countries provide the basis for testing out a prevailing theory about the benefit of screening. Yes, many more cancers are diagnosed once a screening program is introduced, goes the theory, but they are “tomorrow’s cancers” diagnosed today. Then there are the skeptics who look at the long-range statistics and see something quite different. The increase in “tomorrow’s cancers” found in a large group of middle-aged women given regular mammograms, they reason, should eventually result in a corresponding decrease in breast cancer diagnosed later in life.

The skeptics were validated in the Scandinavian study published recently in the British electronic journal, BMJ Online First. After mammography screening was introduced in Norway for women aged 50 to 69 years, the incidence of breast cancer had increased by 54%, according to Per-Henrik Zahl and colleagues at the Norwegian Institute of Public Health, Oslo. The increase was 45% after mammography screening began in Sweden in 1987. Contrary to expectations, there was no corresponding long-term reduction in the rate of women diagnosed with breast cancer. Dr. Zahl and colleagues wrote that the increases in breast cancer incidence were too large to be attributed to causes other than screening, such as hormone therapy.

The significance of these findings is this: Mammography causes many women to be diagnosed and treated for a type of breast cancer that would never produce symptoms or become life threatening if left undetected. Doctors call this overdiagnosis and overtreatment. Unfortunately, most women are not informed of this risk, as they should be, before they consent to mammography screening. A survey of U.S. women’s attitudes toward mammography screening in 2000 showed that only 6% had ever heard that mammograms can find cancers that do not progress.

Whenever researchers address the problems associated with overdiagnosis and overtreatment, they usually focus on the mammography-related massive increases in the diagnosis of ductal carcinoma in situ (DCIS), a type of microscopic cancerous lesion within the milk duct that, in most cases does not progress to life-threatening disease if left untreated. (At least 60% of DCIS will not go on to become invasive and life threatening.).

Dr. Zahl and colleagues, however, have confined their statistics solely to invasive breast cancers, which makes their results even more alarming. The only way women can protect themselves from overtreatment is to give serious thought to the decision whether or not to undergo mammography screening. The risks associated with overdiagnosis and overtreatment are significant enough to make avoiding mammography a reasonable choice for women without breast symptoms. After looking at their survey results, Dr. Zahl and colleagues concluded, “Without screening, one third of all invasive breast cancer in the age group 50-69 years would not have been detected in the patients’ lifetime. This level of overdiagnosis is larger than previously reported.”

Another element of the mammography-related overdiagnosis and overtreatment picture was published within a week of the Scandinavian study. It involves DCIS, which was rare before mammography screening was introduced in the U.S., and now, more than 55,000 women receive this diagnosis yearly. DCIS has been variously called a precancer, a cancer, not a cancer, a high-risk factor. A survey published in the Journal of the National Cancer Institute showed that women are still given unnecessarily aggressive treatment for DCIS (e.g., mastectomy and removal of some of the lymph nodes at the armpit). Conversely, some are undertreated with excision alone for an uncommon type of DCIS called comedocarcinoma that will become invasive and therefore should be treated more aggressively (with radiotherapy).

What you can do:

If DCIS is diagnosed, it is advisable to get a second surgical opinion and a second pathology opinion (see below). With the exception of comedocarcinoma, pathologists are unable to identify which DCIS lesion will progress to invasive cancer and how long it will take to do so.

-To help you decide whether to have regular mammograms, go to this excellent decision-making Web site at the University of California, San Francisco www. mammography.ucsf.edu/inform/index.cfm

-Two of the country’s leading breast pathologists have long been working on ways to distinguish the forms of DCIS that will become invasive from those that will remain dormant. If diagnosed with DCIS, consider a second pathology opinion from Michael Lagios, MD, St. Mary’s Hospital, San Francisco (415) 789-0965 (www.breastcancerconsultdr.com), or David Page, MD, Vanderbilt University, Tennessee (615) 343-0072 (www. breastconsults.com). Both are breast pathologists who will deal directly with breast cancer patients.