To the two certainties of life, death and taxes, add another two: mammograms and controversy surrounding mammograms.
The Canadian National Breast Screening Study (CNBSS) has reported results of its long term follow-up in the BMJ: no survival benefit of screening mammograms.
To paraphrase Yogi Berra “it’s mammography all over again.”
Is the science settled then?
Before I wade further it’s important to understand what is implied by “settling the science.”
Einstein said “no amount of experimentation can prove me right; a single experiment can prove me wrong.”In physical sciences a theory need only be disproven once for it to be cast aside. Heliocentricity cannot coexist with Ptolemy’s universe. The statement “all swans are white” is disproven by a single black swan.
What do we do with the studies that showed survival benefit of screening mammograms? Why does the CNBSS not close the debate over mammograms, like Galileo did with celestial egocentricity?
The simple and simplistic answer is because there are powerful advocacy groups, special interests; the pink-industrial complex who have a vested interest in undermining the science.
But that lends to conspiratorial thinking. Special interests cannot undermine Maxwell’s equations or Faraday’s laws just because they do not like them.
The testability of Maxwell’s equations is inherently different from verifying that screening mammograms increase life expectancy. We must acknowledge two types of science; the former, physical science, a hard science; the latter, a hybrid of biology and epidemiology, soft science.
Soft science is a misnomer. There is nothing soft about performing a randomized controlled trial (RCT), the methodological gold standard; in ensuring factors that falsely augment or attenuate impact of screening mammograms are evenly distributed, data reliably collected, cause of death accurately recorded and correctly inferred. But the human factor and all its inevitable foibles are unavoidable in soft sciences.
The general practice of oncology seems to come in waves of disease. One week every breast cancer patient is in trouble, another sees multiple new cases of lymphoma or leukemia, the next it as if someone is giving away lung cancer (or perhaps cigarettes) and then three patients with pancreatic cancer end up in the ICU. This week a portion of the 240,000 yearly USA cases of prostate cancer walked in our door. The rush of cases served as a reminder that when it comes to this illness, we have a long way to go.
First, Allen. He is 73 years old and has prostate cancer in one out of twelve biopsies. The cancer has a Gleason’s Score of 6 (a measure of aggressiveness of the cancer tissue: more then 7 is particularly bad), which means it is not fast growing. We recommended that given the small amount of slow growing cancer, Allen should be watched without treatment (“Active Surveillance”). What Allen found so difficult about this recommendation is that his son was diagnosed with prostate cancer just one month ago and his son, who is 49, has a Gleason’s 8 Prostate Cancer on both sides of the prostate, and is scheduled for robotic surgery. More than having cancer, Allen is hurt by the feeling it should have been him.
Then there was Robert and Mike. Robert was in the office at 10:00am for evaluation of his newly diagnosed prostate cancer, PSA blood test 32 (high), Gleason’s 7, with evidence of invasion through the capsule of the prostate gland. Fortunately, because prostate cancer likes to spread to bone, his bone scan is normal. Despite Robert’s relatively young age (66), the surgeon recommends external beam radiation therapy (RT) instead of operating. What is bizarre and makes my head spin, was that at1:00pm, in the same exam room, in the same chair, I saw Mike. He has recurrence of prostate cancer, previously treated with surgery. Now Mike needs RT. Although Robert and Mike do not know that the other has cancer, they have worked together in the same small company for 28 years, and consider each other friends.
Politicians and pundits everywhere call for more disease prevention as a way to reduce healthcare costs. Certainly you cannot argue with the logic that “an ounce of prevention is worth a pound of cure.”
Or can you? It turns out that you can not only argue against that so-called logic, but – just as with cancer detection, which may have been done to excess in some protocols — you can mathematically prove that, at least for asthma, it takes a pound of prevention to avoid an ounce of cure.
The database of the Disease Management Purchasing Consortium Inc. (www.dismgmt.com) tracks both asthma drugs and visits to the emergency room (ER) and hospital stays associated with asthma. The average cost of an attack requiring an ER visit or inpatient stay is about $2000. The average cost to fill a prescription to prevent or recover from an asthma attack is about $100. It turns out that asthma attacks serious enough to send someone to the ER or hospital are rare indeed. In the commercially insured population, these attacks happen only about 3-4 times a year for every thousand people. (The rate is much greater for children insured by Medicaid; additional resources spent on prevention could very well be cost-effective for them.)
For a million-member health plan, that might be 3000 or 4000 attacks Yet that same million-member health plan is paying for hundreds of thousands of prescriptions designed to prevent or recover from asthma attacks. Depending on the health plan, the ratio of drugs prescribed to asthma events serious enough to generate an ER or hospital claim ranges from 60-to-1 to 133-to-1. Using those statistics of $2000 per event and $100 per prescription, a health plan would pay, on average, anywhere from $6000 to $13,300 to prescribe enough incremental drugs to enough incremental people to prevent a $2000 attack.
Averages lump together people at all risk levels. Surely some of those people really are at high enough risk of an attack that they are already inhaling their drugs regularly to prevent one, and have a “rescue inhaler” nearby. By definition their risk of attack is much greater than for low-risk people. Assume, very conservatively, that low-risk patients have a risk of attack which is half that of the average patient. This means that putting most low-risk patients on drugs costs $12,000 to $26,600 for every $2000 attack prevented.