Mammography, but at what age?

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In November, major news networks, ethicists, medical professionals, and the public alike were buzzing with surprise in response to newly released recommendations by the United States Preventive Services Task Force (USPSTF) regarding screening mammography for the prevention of breast cancer. The most debated aspect of the recommendation, which differed from the previous recommendations of 2002, specified that women should start getting mammography at the age of 50 instead of 40. It further recommended that women younger than 50 years of age decide individually whether or not to get screening mammography, taking “patient context into account, including the patient’s values regarding specific benefits and harms.”

The 2002 recommendations had concluded that although their meta-analysis showed that the benefit of mammography in the ages of 40-49 was not as large as for women 50 years of age and older (relative risk of death from breast cancer 0.85 versus 0.78, respectively), screening mammography was still recommended starting at age 40. The USPSTF Committee members pointed out that the most important question is what rate of false positives, leading to unnecessary stress, needle biopsies, and cost, are women willing to undergo for the chance of preventing one death from breast cancer? Interestingly, they calculated that for every one prevented death, 400 women would have false-positive results from screening mammography and 100 women would undergo biopsy or fine-needle aspiration. A survey from 2000 suggested that society was willing to accept these risks, with most women surveyed responding that they would accept 500 false positives in mammography to prevent one death.

Since those previous recommendations in 2002, a new trial specifically looking at screening mammography in over 160,000 women aged 40-49 has published data, which has now been added to the data from before 2002. The new calculated relative risk of death from breast cancer using screening mammography remains the same. However, using this new 2009 summed data set, the actual risk of breast cancer, and therefore the absolute risk reduction, in the younger age group of women is less than previously thought. This is best demonstrated with the number of women needed to screen to prevent one death as calculated with all data up to 2009: 1904 women aged 40-49 and 1339 women aged 50-59 years. This can be compared to the 2002 calculated numbers of 1792 and 838 for women 40-49 and 50-59, respectively.

In light of the new controversial recommendations, an amendment was adopted to the Senate’s health care reform bill as proposed by Senator Mikulski of Maryland, which mandated insurance plans to cover (without cost-sharing) women’s preventive services as recommended by the Health Resources and Services Administration in addition to those recommended by the USPSTF. Specifically, this would include mammography starting at the age of 40, consistent with the old USPSTF recommendations.

Commentary

The new data taken into consideration in the recent USPSTF recommendations does show that screening mammography for women ages 40-49 is not as effective as previously believed, although marginally so. Third-party payers may have used the new USPSTF recommendations to deny coverage for screening mammography for women under the age of 50. However, as in 2002, it is debatable how much proven benefit is necessary to outweigh the measurable and immeasurable adverse effects of such screening. No matter your opinion of mammography, the Mikulski amendment leaves the decision on when to begin regular screening mammography in the hands of the physician and patient and ensures third-party payer coverage for those who wish to begin at 40 years of age.

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by
Lisa Maurer, MD