Anthracyclines don’t require an oncologist with a genial bedside manner to slow the growth of tumors.
…the placebo response has limits. It can ease the discomfort of chemotherapy, but it won’t stop the growth of tumors.
Placebo, if it exists as a utile clinical entity (and I’m still not convinced) cannot cure cancer—but chemotherapy can, no matter what hand waving and chanting may or may not accompany it. This goes directly to the concept of “plausibility”. Let me explain.
One of the criticisms of evidence-based medicine, the system of evidence and trials we use to determine what does and does not work, is that it often fails to take into account the plausibility of an intervention. This is what Dr. Harriet Hall calls “tooth fairy science”. A very well-designed trial may, with great statistical significance and reproducibility, determine the average reimbursement for a bicuspid, the average age of children visited by the fairy, the most common perfume worn by the Winged One—but if you fail to examine the assumption that the tooth fairy actually exists, you’ve wasted a lot of time and effort.
When the same thing happens in human medicine, people can die.
The reasons for not bothering to test implausible medical claims are twofold: positive results are statistically likely to be false positives (cf Bayes Theorem), and subjecting people to implausible treatments is dangerous and unethical. Enter the Gonzalez Trial.
The definitive blog posts on the topic are a Science-based Medicine. If you want some depth, go there and read Dr. Atwood’s work. What I’m going to give you is a summary of the topic, and the results of a recent study.
The Gonzalez regimen is a proposed therapy for pancreatic cancer. For some reason, NCCAM decided to put this regimen head-to-head with standard chemotherapy. Our gold standard therapy for pancreatic cancer is not great. Stage IV pancreatic cancer has a five-year survival rate of 1.8%. Reading the NCCAM summary of the Gonzalez regimen is like watching COPS—you’re horrified, but you just can’t turn away. There are many problems, but the most fundamental is the complete implausibility. It is based on a long-discredited hypothesis about cancer that erroneously connects embryonic trophoblast cells with pancreatic development (don’t ask, you’ll just get a headache). The regimen relies on various forms of detoxification:
Two major concepts underlie use of the Gonzalez regimen in cancer treatment. The first concept is that the pancreas, like the liver, is an organ that performs a detoxification function and that pancreatic enzymes help the body eliminate toxins and help normal cells repair damaged cells. The second concept is that cancer and most other human illness are related to physiological imbalances created by environmental toxins either consumed in food or contacted in the environment.
Cancer is fundamentally a genetic disease. What Dr. Gonzalez may or may not understand is that there is a difference between what causes cancers, and what cancers actually are. Sometimes cancers can be caused by toxic substances. For example, certain chemicals can cause changes to a cell’s DNA that effectively render it cancerous. This is not reversible. As the cell divides, it produces more cancer cells. The only way to get rid of them is to surgically excise them or kill them with various types of cytotoxic or radiation therapy. If you have a cancer that was caused by an environmental toxin, it’s too late to remove the toxin—the damage is done.
This is only one of the many reasons that the Gonzalez regimen is implausible, but the fact that it is not even plausible makes it a very foolish thing to study clinically. Aside from the clinical and ethical considerations, the fact that it is so implausible means that any positive results of a clinical study are likely due to chance or bias and not an effect of the regimen.
But in this study, there were no positive results. Of the 55 unfortunate people who were ultimately enrolled in the study, most patients did not live very long—pancreatic cancer is a lousy disease. But the patients in the Gonzalez group lived on average 4.7 months, while those in the chemo group lived on average 14 months. But, you may ask, if the chemo patients lived 9 months longer, might they not have suffered 9 months longer?
No. Quality of life, including pain, was significantly worse in the Gonzalez group.
This study will likely go down in history as one of the least ethical clinical studies ever conducted. It took patients with a bad disease and compared an effective science-based therapy with a completely implausible fake therapy. There was never any good justification for doing this study, and it reflects poorly not just on the investigators but on all of NCCAM.
Chabot JA, Tsai WY, Fine RL, Chen C, Kumah CK, Antman KA, & Grann VR (2009). Pancreatic Proteolytic Enzyme Therapy Compared With Gemcitabine-Based Chemotherapy for the Treatment of Pancreatic Cancer. Journal of clinical oncology : official journal of the American Society of Clinical Oncology PMID: 19687327