New Study: Mammograms Have ‘Limited or No Effect’ on Breast Cancer Deaths

Dr. Mercola

With only a few weeks to go before the annual October rush promoting mammograms begins, a new study published in the Journal of the National Cancer Institute is raising some doubts on mammography’s purported merits.

The findings showed mammograms have little or no influence on reducing the number of women who die from breast cancer … and considering there are serious health risksinvolved, too, what, then, is the point?

Mammograms Again Shown to Have Little to No Value

Breast cancer mortality rates in Sweden have been declining since 1972. Even though this was before mammography was introduced, the reductions have continued and many have attributed it to mammography screening.

The researchers that authored the current study also expected to see a reduction in breast cancer deaths associated with mammograms, but the results showed otherwise:1

“County-specific mortality statistics in Sweden are consistent with studies that have reported limited or no impact of screening on mortality from breast cancer among women aged 40-69.”

In light of these findings, the study’s lead researcher Dr. Philippe Autier, at the International Prevention Research Institute in Lyon, France, noted:2

“Information to women on mammography screening should better reflect uncertainty on the effectiveness of that test, and underline the risk of overdiagnosis and overtreatment.”

And this is not the first time the effectiveness of mammograms has been called into question. In 2010, another study concluded that the reduction in mortality as a result of mammographic screening was so small as to be nonexistent—a mere 2.4 deaths per 100,000 person-years were spared as a result of the screening.3

Mammograms May Cause More Harm Than Good

Many women are under the impression that a mammogram is simply an innocuous test that might or might not help you detect breast cancer sooner. But research shows this screening may end up harming more women than it helps.

Earlier this year, the Nordic Cochrane Center issued a leaflet explaining the potential benefits and potential harms of mammography, stating that, based on the available research, it no longer seems reasonable for women to attend breast cancer screening. After systematically reviewing the randomized trials of mammography, they concluded that:4

If 2,000 women are screened regularly for 10 years, one will benefit from screening, as she will avoid dying from breast cancer because the screening detected the cancer earlier.

Since these trials were undertaken, treatment of breast cancer has improved considerably. Women today also seek medical advice much earlier than previously, if they have noted anything unusual in their breasts…

Because of these improvements, screening is less effective today and newer studies suggest that mammography screening is no longer effective in reducing the risk of dying from breast cancer.

… Since it is not possible to tell the difference between the dangerous and the harmless cell changes and cancers, all of them are treated.

Therefore, screening results in treatment of many women for a cancer disease they do not have, and that they will not get. Based on the randomized trials, it appears that:

If 2,000 women are screened regularly for 10 years, 10 healthy women will be turned into cancer patients and will be treated unnecessarily. These women will have either a part of their breast or the whole breast removed, and they will often receive radiotherapy, and sometimes chemotherapy.

Treatment of these healthy women increases their risk of dying, e.g. from heart disease and cancer.”

So, to recap, in order for mammographic breast screening to save ONE woman’s life:

  • 2,000 women must be screened for 10 years
  • 200 women will get false positives
  • 10 will receive surgery and/or chemotherapy even though they do not actually have cancer

Yet another study, this one published in The Lancet Oncology late last year,5 described the natural history of breast cancers detected in the Swedish mammography screening program between 1986 to 1990, involving 650,000 women. Since breast lesions and tumors are typically aggressively treated and/or removed before they can be determined with any certainty to be a clear and present threat to health, there has been little to no research on what happens when they are left alone.

This study however, demonstrated for the first time that women who received the most breast screenings had a higher cumulative incidence of invasive breast cancer over the following six years than the control group who received far less screenings! The study concluded that:

“Because the cumulative incidence among controls did not reach that of the screened group, we believe that many invasive breast cancers detected by repeated mammography screening do not persist to be detected by screening at the end of 6 years, suggesting that the natural course of many of the screen-detected invasive breast cancers is to spontaneously regress.”

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