Review Finds Few Benefits from Mammogram Screening

Tuesday Jan 20, 2010 (foodconsumer.org) -- A review study by Peter C Gotzsche and Margrethe Nielsen from the Nordic Cochrane Centre in Copenhagen, Denmark suggests that mammogram screening does not reduce the risk of death from breast cancer. The perceived benefits, the study claims, come from bias.

The review of seven trials published in the April 2009 issue of the Cochrane Database of Systematic Reviews showed that overall, mammogram screening reduced the risk of death from the breast cancer by 19 percent.

However, the results of the seven trials, which the researchers found published in PudMed database, are inconsistent.   Three trials with adequate randomization did not show any significant reduction in breast cancer mortality after 13 years, while four trials without adequate randomization found that the screening reduced the risk by 25 percent.

The researchers found the mortality indicated in the trial reports were subject to bias in favor of mammogram screening. This misinformation gained a foothold due to differential misclassification of cause of death.

The trials with adequate randomization found the screening did not have an effect on overall cancer mortality, including breast cancer after 10 years, nor on all-cause mortality after 13 years.

Additionally, Gotzsche and Nielsen found mammogram screening resulted in a 31% increase in lumpectomies and mastectomies; this finding came from a review of the two trials with adequate randomization.  Mammogram screening also increased the use of radiotherapy.

Breast cancer is diagnosed in more than 170,000 women each year in the United States and the disease kills about 50,000 annually.

In the UK, more than 7000 women each year receive false positive diagnoses of breast cancer due to the NHS breast screening program, according to timesonline.co.uk.

Reporting by David Liu and editing by Rachel Stockton