I was disappointed, recently, when I read a handout from the American College of Physicians (ACP) that was designed to help physicians talk to patients about the benefits and harms of screening mammography in women ages 40 to 49. The problem: The summary simply didn’t provide enough relevant information to help patients make an informed choice.
The patient handout was part of a collection of ACP articles that appeared in the Annals of Internal Medicine. (See related POEM.) The first article was a systematic review of screening mammography in women 40 to 49 years of age documenting current data on benefit and harms.1
The ACP also published a clinical practice guideline that included the recommendation that “clinicians should inform women 40 to 49 years of age about the potential benefits and harms of screening mammography.”2 Accompanying that article was a summary for patients.3 Unfortunately, though, this summary failed to provide answers to the following questions: (1) What is my risk of dying of breast cancer if I am not screened? (2) What is the quantitative benefit if I am screened? (3) What is the quantitative harm if I am screened?
Filling the gap between recommendations and practice
To provide patients with the information they need to make an informed choice, I developed a one-page patient information sheet (PATIENT HANDOUT). My handout outlines the benefit and harms as numbers per 1000 women over 10 years, as was done in a recently validated patient education pamphlet.4
I used a readily available epidemiological source5 for the base-case (without screening) breast cancer death risks, and calculated the putative decreases in breast cancer deaths due to screening using the 15% relative risk reduction adopted by the ACP,2 the USPSTF,6 and the Cochrane Collaboration editors.7
PATIENT HANDOUT
Weighing benefit and harms: Mammography for women, ages 40–49
For every 1000 women in their 40s, what are the benefits and harms of mammogram screening over a period of 10 years?
| WITH MAMMOGRAMS OVER 10 YEARS | WITHOUT MAMMOGRAMS OVER 10 YEARS | LIVES SAVED PER 1000 WOMEN SCREENED WITH MAMMOGRAMS OVER 10 YEARS | |
|---|---|---|---|
| BENEFIT OF MAMOGRAMS | Breast cancer death | Breast cancer death | |
| • Less likely to die from breast cancer1 | Black women 3.6 White women 2.1 Other women 1.3 | Black women 4.2 White women 2.5 Other women 1.5 | Less than 1 Less than 1 Less than 1 |
| HARMS OF MAMOGRAMS | Harms of screening | ||
| • More likely to have false alarms2 | 450 | None | |
| • More likely to have unnecessary diagnosis and treatment for breast cancer3 | 5 | None | |
| • More likely to have pain or discomfort from mammography4 | 320-550 | None | |
| • More likely to have radiation exposure5 | 1000 | None | |
| • More likely to have false reassurance6 | Uncertain | None | |
| 1The benefit of mammograms may be larger if you are at higher risk, or the benefit of mammograms may be smaller or even zero if the best quality research studies are correct. | |||
| 2False alarms are abnormal results that are not cancer, leading to unnecessary repeat mammograms, biopsies, and worry. | |||
| 3Not all cancer detected by mammography will cause symptoms or death. This is because not all cancers will continue to grow or spread. Doctors cannot always tell which cancers detected by mammography need treatment and which do not need treatment. | |||
| 4Many women complain of temporary discomfort or pain during mammography because the breasts are squeezed. | |||
| 5All mammography uses radiation. Doctors do not know whether this radiation causes cancer, but most doctors believe the harm is very small or nonexistent. | |||
| 6Some women who develop breast cancer before their next screening mammogram might delay treatment because their previous mammogram was normal. | |||
The science behind the bullet points
I kept the grid simple, but recognize that my colleagues would appreciate knowing where the numbers came from, and what was the basis for certain explanatory statements. So here is some background on the first three bullets.
- “Benefit: Less likely to die from breast cancer.” The explanation (#1) that is tagged to this statement notes that the benefit of mammograms may be larger if a woman is at higher risk. This statement was taken from the ACP meta-analysis and guideline.1,2 The second part of this explanatory sentence, which indicates that “the benefit of mammograms may be smaller or even zero if the best quality research studies are correct” is based on the results of the Cochrane Review7 and is acknowledged in the ACP guideline.2
- “Harm: More likely to have false alarms (false positive mammograms).” I presented the percentage of false positive mammograms as 45% based on the 5-year (30%) and 10-year (56%) false-positive percentages reported for the Harvard Pilgrim Health Care study by the ACP.2
- “Harm: More likely to have unnecessary diagnosis and treatment for breast cancer.” I listed the number of women likely to suffer this harm as 5, based on the Cochrane Collaboration Review on screening for breast cancer with mammography.7