Several of my blogs have dealt with various forms of bad medicine. Most recently in "Cancer Hope or Hype?" I presented an example of documented fraud in chemotherapy sensitivity and resistance assays. Labs providing these assays have sprung up like weeds on a wet spring day and many naive patients and clinicians have been swayed by their claims, in spite of a lack of documented efficaciousness. We frequently get requests from our clinicians and patients to perform these highly expensive tests. Refusal to comply, even when accompanied by a carefully thought out rational reason, usually leads to something resembling a childhood temper tantrum accompanied by a string of derogatory comments ranging from, "you guys are so backward," to "you're killing my patient."
Undoubtedly, many of you have been confronted with exactly this scenario, and you may well have buckled to the strident demands and sent appropriate materials off for the favored assay de jour. In many instances your department may then have been forced to "eat" the exorbitant charges when neither the patient's insurance carrier, the patient or (heavens no!) the requesting physician would cover the charges.
Well, guess what? The American Society of Clinical Oncologists (ASCO) has just given you an extremely powerful bit of ammunition for your refusal to order these highly expensive and highly questionable (resisting the urge to use the word "worthless" here) tests. In the August 20th issue of the Journal of Clinical Oncology
, ASCO has published its "Clinical Practice Update on the Use of Chemotherapy Sensitivity and Resistance Assays (CSRAs)." This paper is a short, well-written tribute to evidence-based medicine. If you're in a hurry, here's the bottom line:
"The use of CSRAs to select chemotherapeutic agents for individual patients is not recommended outside of the clinical trial setting. Oncologists should make chemotherapy treatment recommendations based on published reports of clinical trials and a patient’s health status and treatment
Importantly, this is EXACTLY the same recommendation that the ASCO group reached in 2004! That's right, in the last seven years, despite a huge number of reports and hype, there has been NO CONVINCING EVIDENCE that these studies are clinically efficacious on a case by case basis.
This report deserves a bit more attention, and can be quickly read if you've got the time. In brief, at the request of the ASCO leadership, the eight authors of this study began with a review of over 11,000 abstracts published in the English language literature between December 1, 2003 and May 31 2010 and dealing with human clinical oncology. Search terms including "controlled trial, "meta-analysis," "guidelines," and "review," wittled this group down to only 21 articles that were reviewed in detail. Included in this group were five randomized clinical trials, which are reviewed in the text. The raw data from this study, including the search guidelines, are available as an on-line data supplement
It should be noted that the authors confined their review to in vitro assays using viable tumor cells, analogous to bacterial antibiotic sensitivity and resistance assays that measure growth inhibition in the presence of an antibiotic diffusion gradient. These are generally considered the most direct (and potentially most valid) assays for assessing tumor cell sensitivity and resistance. The authors did not review assays performed on non-viable tumor tissues by immunohistochemistry, gene expression or transcript profiling. I can't help but wish that the authors had specifically addressed these forms of CSRAs as well, yet you should note that the guidelines make no distinction with regard to the manner in which the CSRA is performed. If direct tumor cell sensitivity and resistance assays are not efficacious on case by case basis, the authors seem to conclude (rightly, I believe), that more indirect assays should not influence treatment either.
Print out some copies of this paper and keep them handy. In all likelihood you'll need them.