I have watched the rhetoric and heated debate about screening at age 40, now 45, and 50 for 25 years and am miffed that the discussion consistently ignores the obvious things we can do to save lives.
All bodies (North American and European) that publish guidelines recommending screening say that all healthy women over 50 should get routine screening.
It is widely accepted that more than a third of American women over 50 do not get regular mammography and some do not get good quality mammography. It is also accepted that a good proportion of American women with diagnosed breast cancer do not receive good cancer treatment. It is a fact that the number of lives that could be saved by the logistical move of providing quality care to all is far greater than the number of lives that might be saved by screening all women in their 40s.
The following are my own views. They should be interpreted as the opinion of a physician who has studied screening for nearly three decades and been concerned about ethics in medicine and doing the right thing to save the most lives and prevent the most suffering.
In 2011, the Institute of Medicine of the National Academies published a study with guidelines on the creation of trustworthy medical guidelines. The IOM study was commissioned because many of the healthcare guidelines of the past two decades were based on the opinions and prejudices of those writing the guideline and often not based in science. It was well known that some guidelines authors were clinicians with financial interests and limited expertise in the subject area. This was especially true of cancer screening guidelines.
The IOM’s goal was to remove those with emotional and financial conflicts of interests from guidelines processes and replace them with a group of people who have objectivity and expertise. The IOM also said a guidelines committee should commission a structured review of the relevant scientific literature and each published research study should be graded. This is an important point. Some published medical studies are of very high quality, but some are not, some are biased. One can only get close to finding the truth by rigorously evaluating the quality evidence and discounting poor science.
The American public has been conditioned that all cancer screening is good. This is partly because cancer is understandably an emotional issue and partly because of a lack of understanding of complexity of cancer screening. There has long been a tendency to exaggerate the benefits of cancer screening and minimize or even ignore the harms associated it.
In the case of mammography for breast cancer, there have been years of overly simplistic messaging hyping the benefits and not recognizing the limitations. When I say limitations, I note that numerous expert panels have examined the data and agree that clinical trials suggest mammography reduces relative risk of death by 20 percent. Many expert panels agree that some observational studies suggest mammography may reduce relative risk of death by as much as 40 percent. This most optimistic assessment means mammography when done well does not benefit 60 percent of the women who need it.
Any criticism of mammography or mention of limitations seems to upset the real believers in screening. It is mistakenly viewed as antimammography and giving women an excuse not to get the test. Many in the lay and medical community have been allowed to believe mammography is near 100 percent. This is one reason why mammography is a leading cause of medical malpractice suits.
The above statement should not be construed as against the use of mammography, it is a plea for cautious, wise use of a technology that can be beneficial, but can also be harmful. A message we should be telling the public is: There is some benefit to mammography screening. But we do need a better screening test. Until a better test is developed, we need to wisely use the technology we have.
After nearly two years of study, a committee of experts commissioned by the ACS and using a modified IOM format issued a breast cancer screening guideline for women at average risk. The experts saw benefit in mammography screening saying it clearly reduces risk of death. That is “epi speak.” The colloquial lay translation is “screening saves lives.”
They also noted that breast cancer is relatively uncommon among women aged 40 to 44 and screening does not work well in populations where the disease of interest is uncommon. In this population at low risk for breast cancer, there are many false positives in order to detect the (relatively) few that can be helped by early detection. These objective experts examined the data and did not see that the benefits clearly outweigh the harms, when screening the entire population aged 40 to 44, but they do recognize that some women this age do benefit.
Largely overlooked in coverage of the announcement was an important detail. The panel said all women aged 40 to 44 should be informed of the potential benefits and potential risks of annual screening and be encouraged to make a choice. They chose not to be paternalistic. In an area where the science does not support a clear advantage versus harm for the general population, let the individual decide for herself. Screening should be tailored to the individual woman’s concerns by the woman herself.
I would note that such informed decision making is not controversial in the world of prostate or lung cancer screening. The ACS recommendation even says those women aged 40 to 45 who want screening should not face financial barriers to getting that screening.
Some screening advocates seem unable to accept the fact that there are limitations to our current screening technologies even though there is significant consensus about this among experts. In recent years, 12 committees of screening experts in the U.S., Canada, or Europe have said that there is a problem in screening all women in their early 40s. Indeed, I cannot name a group of objective experts, who have gone through a process of reviewing the scientific literature, and still support widespread screening of women in their early 40s.
This guideline applies to women of average risk. If we are truly interested in saving lives, we will support research to improve our ability to identify the young women who are at a high risk for breast cancer and likely to benefit from current screening technologies, and efforts to develop better screening tests.
I believe the new ACS guideline moves closer to revealing the truth about the strengths and weaknesses of breast cancer screening. It encourages women to make their own personal decision about screening. Mammography can save lives and we can use in wiser fashion to maximize its benefits and minimize its harms while supporting efforts to find a more effective test.
The author is chief medical officer of the American Cancer Society.
