Thursday, February 21, 2013

Should screening mammography always be a shared decision?

In the February 15th issue of American Family Physician, Dr. Maria Tirona reviews areas of agreement and disagreement in major organizational guidelines on screening for breast cancer. There is widespread consensus that annual or biennial mammography should be offered to women 50 to 74 years of age, and that teaching breast self-examination does not improve health outcomes. For women 40 to 49 years of age, in whom the risks and benefits of mammography are closely balanced on a population level, the U.S. Preventive Services Task Force and the American Academy of Family Physicians recommend shared decision making, taking into account individual patient risk and patients' values regarding benefits and harms of screening.

In an accompanying editorial, however, Drs. Russell Harris and Linda Kinsinger argue that shared decision making regarding breast cancer screening need not be limited to younger women:

More and more, the goal for breast cancer screening is not to maximize the number of women who have mammography, but to help women make informed decisions about screening, even if that means that some women decide not to be screened. ... The goal of improving patient decision making should be expanded to all women eligible for breast cancer screening (i.e., those 40 to 75 years of age who are in reasonable health), because the benefits and harms of screening are not very different among these age groups.

The primary benefit of screening mammography is an estimated 15 percent relative reduction in deaths from breast cancer; harms of mammography include false positive results, overdiagnosis, and overtreatment. A recent study published in BMJ explored the impact of overdiagnosis on attitudes toward mammography in several focus groups of Australian women 40 to 79 years of age. Few women had ever been informed about overdiagnosis as a potential harm of screening. Most women continued to feel that mammography was worthwhile if overdiagnosis was relatively uncommon (30 percent or less of all breast cancers detected). However, a higher estimate of overdiagnosis (50 percent) "made some women perceive a need for more careful personal decision making about screening."

Notably, a 2011 Cochrane Review estimated that 30 percent of breast cancers detected through screening are overdiagnosed:

This means that for every 2,000 women invited for screening over 10 years, one will have her life prolonged, and 10 healthy women who would not have been diagnosed if there had not been screening will be treated unnecessarily. Furthermore, more than 200 women will experience important psychological distress for many months because of false-positive findings.

Given this information, what approach should doctors take with screening mammography? Do you believe that this test should be routinely provided to women of eligible ages, a shared decision for some, or (as Drs. Harris and Kinsinger advocate), a shared decision for a woman at any age? Why is it often difficult to promote such shared decision making in clinical practice?


The above post was first published on the AFP Community Blog.


  1. You pose great questions. Time is our biggest foe. No one comes to the doctor's office just to talk about mammograms. They come for a sore throat and are offered mammograms, pap smears, colonoscopy referrals, tetanus, flu, diabetes and cholesterol screening, etc. While this is the essence of a medical home, finding the time to truly counsel the patient about any one of these topics is difficult as the patient often has on her agenda more than just the sore throat. I have yet to find a tool that quickly assesses breast cancer risk and provides something in writing that adequately explains the risks/benefits so that a woman can at least take that with her to review after the visit.

  2. The other problem is the lack of respect for informed consent and even consent itself in women's cancer screening. We hear over and over we "must" or " should" screen and non-screeners are called uneducated, lower class, reckless etc; we get very little real and unbiased information.
    Basically you can't make an informed decision unless to do your own research and then stand your ground in the consult's usually unacceptable for women to decline cancer screening, you may get a lecture, rudeness etc...precious consult time is also lost to pap test pressure. Opportunistic testing has always been promoted by Papscreen. Studies have shown that opportunistic testing can lead to psychological damage. No wonder some women avoid doctors because of this pressure....buying the Pill and other meds online.

    Cancer screening should always be our informed decision, instead we get scare campaigns, misinformation, an emphasis on screening targets, even our GPs get target payments. (never disclosed to women)
    Until about 15 years ago, women were "required" to have a pap test (and unnecessary breast and pelvic exams) to get the Pill. This was a tactic used to increase coverage, IMO, coercion negates all consent. Women were often denied reliable contraception if they declined the excess, risking a unplanned pregnancy, abortion, ectopic pregnancy or miscarriage.
    A medical clinic in WA has on their website, "women on the Pill need pap tests"...this is like saying men using condoms need prostate exams.
    So shared decision making is light years away in women's cancer screening....and has always been strongly resisted.

    I got to the facts more than 30 years ago and have aways refused pap tests and more recently declined mammograms. I did not get the information I needed from doctors or the Cancer Council, but had to do my own research. The Nordic Cochrane Institute have produced an excellent summary of all of the evidence, "The risks and benefits of mammograms" is at their website.
    Women who want to test for cervix cancer should look at evidence based programs found in the Netherlands and Finland. Since the 1960s the Finns have has a 6-7 pap test program, 5 yearly from 30 to 60. The Finns have the lowest rates of cc in the world and refer far fewer women for over-treatment/excess biopsies. The Dutch have the same program, but will introduce a new program, 5 hrHPV primary tests (or self test with the Delphi Screener) at ages 30,35,40,50 and 60 and only the roughly 5% who are HPV+ and at risk will be offered a 5 yearly pap test. Most women are HPV- and cannot benefit from pap testing. This will save more lives and spare the vast majority of women from a lifetime of unnecessary pap testing with the fairly high risk of over-treatment. More Aussie women are getting to the facts...the HPV self-test device can be ordered online, you test yourself and mail your sample back to Singapore, your results arrive by email. Women can then make an informed decision, HPV+ and you have a small chance of benefiting from a 5 yearly pap test...most women are HPV- and cannot benefit from a pap test, these women will be advised to re-test in 5 or 10 years time (depending on age) to cover the possibility of a new infection. Those women HPV- and confidently monogamous or no longer sexually active might choose to stop all testing.
    I don't know what we're doing in this country, we maximize risk for no additional benefit and we don't offer HPV primary or self-testing, just excessive pap testing.
    Our program is outdated and harmful, we spend millions to basically worry and harm women. This program needs urgent review by a independent body like the NCI....otherwise profitable excess is likely to remain into the future. See: Delphi Bioscience on HPV self-testing and HPV Today, Edition 24, for the new Dutch program.