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Tuesday, December 8, 2009

mammogram screening, take 2

I finally read through the 3 articles in the Annals of Internal Medicine that addressed the new recommendations from the US Preventive Services Task Force (USPSTF) about the recommendations for mammogram screening and breast exams. These have led to angry reactions, mostly based on lack of information and lack of understanding of the science behind the recommendations.

First of all, the USPSTF is far from the only organization to weigh in on screening recommendations. There are organizations such as the American Cancer Society, the American College of Obstetrics and Gynecology and various other official groups from various branches of medicine. The USPSTF is, however, the most evidence based of the groups, the least financially motivated, and the most conservative.

The recommendations of the USPSTF are categorized according to how sure they are that they are right, and changes come after long discussion and detailed evaluation of the research and the opinions of other organizations. In 1996 they were unable to endorse regular mammogram screening for women younger than age 50, but in 2002, based on information from studies done since that time, they extended their recommendations to women starting at age 40. They acknowledged at that time that there were risks associated with mammogram screening and that it was neither sensitive nor specific during that decade.

Yet more studies have become available since that time and the recommendations have gone back to encouraging women to begin mammogram screening at age 50, saying that screening before that time should “take patient context into account, including the patient’s values regarding specific benefits and harms.” They conclude that evidence is insufficient to recommend screening of women 75 years and older, which is solidly in line with recommendations in European countries. They do not, however, recommend against screening in older women.

The decision not to recommend mammograms routinely for women ages 40-49 is based on the fact that mammograms often pick up abnormalities of the breasts which appear suspicious, result in further procedures, and harm women through over treatment and excessive diagnostic testing. Breast cancers are detected in that decade, but the risks of screening all of those unaffected women outweigh the benefits of early detection in the few.

The recommendation that women not be taught breast self examination has engendered the greatest amount of misunderstanding of all. On the face of it, it makes no sense. What harm could self examinations do? Why should a woman not know her own body?

The recommendation is based on two large studies, one in Russia and another in China, evaluating self breast exams in a population that did not get regular mammograms. Women who were taught breast self examination techniques had no benefits in terms of breast cancer survival when compared to women who were not. So this recommendation really addresses the question of whether a physician should spend time specifically teaching women techniques of self breast examination. It does NOT say that doctors should now tell women not to examine their breasts. Perhaps women are just fine at examining their breasts without being harangued by their doctors to do so.

What, you may ask, is the rationale behind getting mammograms every 2 rather than every one year? Studies have shown that as many as 99% of breast cancers are picked up by every other year mammograms, and given known harms of radiation and associated costs of those extra mammograms, were they done every year, 2 year intervals seem like they are the magic number.

But why 2 years? What’s so special about the number 2?

At the Norwegian Institute of Public Health, studies have looked at women who got mammograms every two years for 6 years vs women who got only one mammogram at the end of 6 years. The women who got the mammograms every 2 years had a significantly higher incidence of breast cancer than the ones who got only one mammogram, and this difference persisted in the years that followed. The conclusion that the Norwegian doctors came up with was that the every 2 year screened women had breast cancers discovered which would have gone away if left untreated. American researchers have hotly disputed this interpretation, but their arguments are not compelling.

It is clear to me that the recommendations of the USPSTF to reduce recommended mammogram screening is NOT based on a politically motivated desire to reduce health care spending at the expense of the health of women. It is not yet clear to me what the best recommendations for mammogram screening should be. I intend to continue, as I have, to discuss with patients the pros and cons of mammogram screening and help them make the choices that are best in line with their risks and their values.

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