In an earlier essay I drew parallels between efforts by the Spanish Inquisition to root out heresy, police entrapment in drug cases, police entrapment associated with the War on Terror, and the use of increasingly sensitive medical tests to diagnose conditions, notably cancer, in order to induce people to consume medical products and procedures of questionable utility. An incident this week provided an excellent example of the medical aspect of this equation.
My Medicare coverage, which I maintain partly because it satisfies the coercive aspects of Obamacare and partly because it does provide hospitalization coverage, is handled by Pacific Source, an umbrella HMO. I have not used it in the nearly five years I have been on Medicare, although I have experienced health problems in the interim for which the average American consults a doctor, and was repeatedly offered a “free” comprehensive health evaluation when I first enrolled. My current health, based on lack of symptoms and evaluations I can do myself, at home, is good.
Earlier this week I received a packet from Pacific Health containing a “Fit-Check” home kit for testing for colon cancer, or rather (if you read the fine print) for occult blood in a stool sample, which can be a sign of colon cancer but much more commonly is a sign of benign adenomas (polyps), which affect about 30% of adults over 65. I knew that I was dealing with a test which produced an inordinate number of false positives, which if nothing else would trigger pressure to undergo a colonoscopy, an invasive procedure of doubtful diagnostic utility. I was going to simply throw the kit away, but opted instead to go online and investigate some of the primary research literature with a view to determining just how prevalent the false positives were and what evidence there was that all of the testing, both of stool samples and colonoscopies, had been responsible for improvement in colon cancer outcomes in the United States since testing became widespread.
To make a long story short, the prevalence of false positives (finding evidence of cancer where no cancer existed) in the occult blood tests was very high and affected large numbers of people, while even with increasing test sensitivity false negatives (failure to detect cancer when it was present, thus giving people a false sense of security and depriving them of the benefits, if any, of early treatment} were also a problem. Although rates of new diagnosis of colon cancer and death rates from colon cancer have declined steadily and significantly in the last twenty years, more or less in tandem, the data simply do not support concluding that all this testing has been an important factor in the decline, although that is the conclusion that reaches the ears of the public and the desk of the average MD.
The first study I found: “Test Characteristics of Fecal Immunochemical Tests (FIT) Compared with Optical Colonoscopy Revised” JMS-14-003.R2 was a study involving somewhat over 1,000 healthy, not exceptionally high risk older Americans who were tested using several brands of fecal occult blood kits of the current type, and shortly afterwards had colonoscopies. The effectiveness of the newer tests, versus an older test whose sensitivity and effectiveness had proven less than satisfactory in clinical practice, was the issue being investigated. Of the 30% of this population who had benign polyps, half tested positive and half negative. Neither of the two individuals whose cancer was discovered in a colonoscopy tested positive. Although the data basically demonstrated, rigorously, that these tests given on a population level would not result in more accurate identification of early stages of colon cancer, and also did not demonstrate any difference with respect to the earlier tests which had proven unsatisfactory in clinical practice, nonetheless the authors of the article recommended adopting this testing regime for populations for which routine colonoscopies were not practical. That conclusion or something similar must have reached the desks of my HMO and persuaded at least some people that a mass mailing of home test kits to their subscribers was a good idea, not just for the bottom line of the HMO, but for the health of their clients.
Also buried in this article were two quotes, which, taken together, allude to studies showing that neither colonoscopies nor fecal blood tests are particularly effective at reducing colorectal cancer mortality – another finding that does not seem to have reached the scrutiny of my HMO, or, if it has, they have ignored it. “These [European] guidelines reported limited evidence for the efficacy of colonoscopy in reducing CRC incidence and mortality”.7 and “A decision analysis performed for the United States Preventive Services Task Force found no difference in life-years gained by CRC screening using colonoscopy every 10 years vs. annual testing with a sensitive FOBT or a FIT in individuals aged 50 to 75.”15
The second source, the website of the US Center for Disease Control, shows trends for diagnosis and mortality for colorectal cancer between 1999 and 2015. According to this site, death rates from colorectal cancer declined from 20 per 100,000 in 1999 to 15 in 2015, or roughly 25%. It does not say if these rates are age adjusted but elsewhere on the page it gives aging population as a cause for the increase in total deaths in the US from CRC in the same period.
During the same period, rates of newly diagnosed cases went from 58 to 41, a 34% drop. Combining these two figures, the rate of cases which proved lethal was 34% in 1999 and 36% in 2015. This suggests that early detection programs are not having a positive effect on eventual outcome although they may increase survival time following diagnosis (which would be expected even if treatments were ineffective.) The pattern points to some other factor besides screening and subsequent aggressive treatment being responsible for the decline in incidence. For comparison, stomach cancer mortality, for which there is as yet no screening program, declined markedly in the US between the mid-1950’s and 1999; it is one of two cancers (lung cancer being the other) which have declined significantly in the US in my lifetime. The cause is almost certainly environmental and eliminating nitrites, certain fungi, and asbestos from food production is a plausible explanation.
One way to market a product or service purported to address a particular problem is to identify an existing trend in decline of that particular problem before it has reached the general public radar, time the release of one’s product or service to coincide with the decline, and claim credit through the common and difficult to recognize fallacy of confusing correlation with causation. This may be occurring here.
Photo courtesy of Martha Sherwood