Does Screening Mammography Save Lives?

Breast cancer is a topic that seldom evokes dispassionate, let alone objective, treatment.

There is good reason for that. We all know, often intimately, of the tragedy this cancer can cause.

Furthermore, the topic roils with gender issues and other issues of bias in the provision of health care. No one should be deprived of effective care of the highest quality for any reason, including gender and ethnicity. We need to address past wrongs.

However, past wrongs and current tragedies do not excuse providing remedies that are ineffective. It is under this banner that I want us to calmly and objectively examine the effectiveness of screening mammograms. I have done so before, in detail in "Last Well Person." I do so today because of the chest-pounding about the decrease in the numbers of women submitting to mammograms and the auguring about a consequent rebound in breast cancer incidence.

Examining the Numbers

First, let me make certain we all understand what is meant by "screening mammography."

Screening is a public health initiative. It is advised that all women of a certain age should submit to mammography periodically, regardless of whether or not they have any particular personal concerns.

The rationale is that screening will lead to more good than harm for the public at large by identifying those women who are unaware of a treatable breast cancer.

Women who forego screening can still turn to a physician with any concern, such as feeling a lump or nipple discharge. The physician may even order a mammogram to decide whether or where to biopsy. That is not a screening mammogram; that is mammography used as diagnostic test for a specific reason in a particular patient.

Back to screening mammography: Let me tell you about the women of Malmö, Sweden. In 1976, half of the women between the ages of 44 and 68 were randomly selected and invited to participate in mammographic screening every 18 to 24 months for a decade. All the women -- both the screened and unscreened -- were followed for another 15 years after that decade.

Over these 25 years, 9,279 of the 21,000 in the invited group, and 9,514 of the 21,000 in the control group, died of various causes.

In total, 1,320 women in the invited group were diagnosed with breast cancer, and 212 died from the disease. Breast cancer was detected in 1,205 women in the study's control group who did not get routine screening, and 274 of those women died from their breast cancer.

The difference between the two groups is not considered statistically significant. So whether or not women received screening mammography did not seem to affect the chances of their doctor detecting a breast cancer, regardless of their age.

Randomized, controlled trials of screening mammography from Canada and Stockholm have results similar to the Malmö trial.

Huge Effort, Questionable Benefit

Could this be? Screening mammography is an inalienable rite of passage, a mantra for "health promotion, disease prevention" and an industry. Have we been deluding ourselves?

Maybe trials such as the Malmö trial are asking the wrong question. We don't screen to find cancer. We screen to find the cancer that would kill a woman before her time unless it is detected early and treated appropriately.

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