The cost-benefit rationale for the U.S Preventive Service Task Force report
Given how standard the mammogram had become, and how strongly its use had been encouraged by the medical establishment, how could the U.S Preventive Services Task Force have departed so significantly from this consensus?
The Task Force based their recommendations on a cost-benefit analysis. Using mathematical modeling procedures, they calculated that for woman not in high-risk categories, the negatives of routine mammograms generally outweighed the positives for women between the ages of 40 and 50. Based on this calculation, they suggested that women turning 40 should decide on whether to start having regular mammograms based on discussions with their doctors about their own particular risk factors, instead of just doing it automatically. Overall, the Task Force estimates are that about one life could be saved for every 2000 who turned forty if all were to receive screening mammograms annually for a period of ten years.
The major negatives of mammography identified by the Task Force were:
- False positives – only about 10% of women who show abnormalities on mammograms will ultimately be diagnosed with cancer, which means a lot of anxiety and stress and extra expense for the 90% who will eventually be given an all-clear after further testing
- False negatives – about 20% of cancers will be missed on mammograms, which can be a problem if these cancers are fast acting and aggressive
- Too early treatment – many breast cancers develop slowly without metastasizing, meaning they could easily be treated later rather than earlier
- Overdiagnosis – many cancers will never actually develop and evolve into a real health threat, and many more might be defeated by the body’s immune system, meaning these cancers are being treated unnecessarily
- Expenses – the cost of all of this testing and treatment can cause a lot of financial hardship
The personal cost-benefit analysis
To put things in perspective, the 1 out of 2000 ratio mentioned earlier means that approximately 1,200 lives can be saved through earlier detection by mammogram if all 23 million women between the ages of 40 and 50 were to take regular screening mammograms. Based on this equation, the American Cancer Society has not changed their belief that regular mammography should begin at 40, nor have doctors stopped recommending it to their patients. Even though the ACS has accepted this calculation in arguing that even a few extra lives saved are worth the risks and inaccuracies, it should be pointed out that other studies done on the question have come up with higher estimates for the number of lives saved by screening (although other studies largely concur with the Task Force).
The Task Force’s mission has perhaps not been well understood by everyone. Their findings and recommendations were only intended to provide information and guidance, and were not intended to change of influence government or medical policy. In addition, their recommendations were not directed at women who are in high-risk categories, as everyone agrees they need more frequent testing. Women will still be completely free to begin taking regular screening mammograms whenever they want but they may want to carefully consider all of the possible problems and difficulties that might arise if they do. If they should decide to forego regular screening mammograms while in their 40s, it appears that the likelihood of it ultimately costing them their lives is small. However, the possibility is not nonexistent. In the end, each woman will have to do her own cost-benefit analysis, and decide for herself if waiting until age 50 to begin regular screening mammograms is a risk she wants to take.
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