May 30, 1997
I am a firm believer that the public has a right to know.
While most people will pay little attention, there are some of
us who use the best information that we can get to try to live
longer and better lives I deeply resent any attempt to conceal
information. Having accurate information enables people to make
wise decisions.
I am writing this on a Boeing 737 on a flight that is bringing me home from a meeting of the American Association for Cancer Research. There was a dearth of discussion of mammography. Presumably, the issue has been settled and there is no need to bother the public with talk of the risk of x-ray; just the risk of dying of breast cancer. Those people who determine what the public will hear about the subject have apparently decided that if people are told that x-ray will cause cancer, they will be cautious about getting x-rays. As a consequence of that fear, some women might not get mammograms.
Physicians have been taught about risk in medical school. A few are even aware of its implications -but not too many. The prevailing attitude is that if some procedure has a small amount of risk attached to it -and what treatment doesn't?- it is considered as having no risk at all. At least that is what the patient is told: "It is safe!"
Most members of the public -at least the more mature members of the public- are quite aware of the concept of risk. Anyone who drives an automobile or flies in an airplane is aware that there is a chance that you might be killed. The chance is relatively small, so most of us don't worry about it. With the automobile, sensible people take precautions to reduce the risk as much as possible and with the airplane we rely on the skill of the pilot, the airlines and the FAA to keep the risks minimal. Many people believe that dying of cancer is much worse than dying in an automobile accident. I think that they are mistaken -dead is dead!
Many of us are also aware of the concept of "competing risks," although most people are not familiar with the term. Simply put, it tells you that if you are going from San Francisco to San Diego, your chances of being killed on the trip are greater if you drive that they would be if you took an airplane. How are these competing risks determined? You simply take the number of deaths in car crashes divided by the total number of miles traveled, and you do the same thing with air travel. Air travel wins. So, unless you have some compelling reason for driving, such as wanting to make stops along the way, or see the scenery, air travel is much safer. It is usually a lot less stressful -at least it is for me.
The same principle holds with mammograms. If you are a woman over 50, your chance of dying of breast cancer is less if you have a mammogram every year or two. While no one knows for sure what the exact risks are, there is agreement that if you are under 40, it seems likely that the risk of dying of breast cancer will actually be increased by getting regular mammograms. This is because x-rays can cause breast cancer, as well as other types of cancer. If you are a member of a "cancer family," this all changes because the cancer risk is much greater than it is for most women.
The public is being informed of the benefits of mammography, without being told of the risks. This is like giving your teenage son the keys to the car without educating him about the risks of driving an automobile. As a consequence, there are some women who get many more mammograms than they need because they are terrified of breast cancer -in part a function of the campaign to get women to have mammograms.
The risks of dental x-ray were trivialized 30 years ago. Lead aprons were not used to protect children and young adults, who are at the greatest risk of getting radiation induced cancer and gene mutations. Some of these people -I have no idea how many- had children with birth defects and some got cancer. True, the numbers are very small, but the risk could have been reduced just about to zero by using a device as simple as a lead apron.
All mammograms are not the same. Some are much better than others. Some laboratories use equipment and processing that gets the best results obtainable, with the minimum amount of radiation exposure. Some radiologist are more competent at reading the films; much of this as a consequence of extensive experience. If you ask around, you can usually locate those better radiology laboratories.
We are asked to believe that dentists and physicians do what they do for the benefit of their patients and that money doesn't enter into the equation. The fact that radiologists profit from mammograms and dentists profit from x-rays -we are told- does not enter into the decision whether to order x-rays or not. Therefore, we are asked to put our lives , and the lives of our children, in their hands without question.