The wonderful thing about this site is we are free to post anything we want within the bounds of civility. But that is also a danger - many people post studies without regard to truth. Truth is judged by the scientific process.
Two studies this week illustrate why patients should never use retrospective observational studies on drugs to make treatment decisions: metformin and cholera vaccine.
Metformin
I won't say yet that metformin has been conclusively proven to have no effect in prostate cancer (we await definitive results of the STAMPEDE trial). But I will say that all the upper level evidence is so far against it. And there is a proven increase in serious side effects from using it. Again, here's our best quality evidence so far:
prostatecancer.news/2019/11...
Cholera Vaccine
As for cholera vaccine, here is what was posted by George71, Nalakrats, LearnAll, etc. on this site 3 years ago:
healthunlocked.com/advanced....
healthunlocked.com/advanced...
healthunlocked.com/advanced...
Here was my response at the time:
"Association is NOT causation. There were 89,142 men in the Swedish registry, but only 841 (1%) men who received the vaccine to prevent cholera. The first suspicion is "selection bias" - in what ways were the men who got the vaccine DIFFERENT from most men? I suspect there were more health care workers who are more attentive to catching diseases (including prostate cancer) early, more educated, and may have gotten a wide range of other therapies (e.g., chloroquine, an anti-malarial, has some effect on PC cells in lab studies). These suspicions are borne out in Table 2. Cholera vaccine users were:
- Younger
- Diagnosed earlier
- More educated
- Higher income
- Diagnosed at an earlier stage
- Less likely to have comorbidities (diabetes, heart disease, COPD, hypertension)
Even with statistical adjustment (which assumes significant overlap), the biases are way too large and unmeasured confounding variables (like PSA testing, chloroquine use, lifestyle, diet, smoking, health care workers) too important to draw any useful conclusions."
Today the Swedish researchers wrote:
"Therefore, we conclude that this effect is most likely due to a healthy traveler bias and is an example of residual confounding."
sciencedirect.com/science/a...
This is not to toot my own horn, but I spent 20 years on the job studying research methods and statistics. It is not easy. Why one study is only useful for hypothesis generation and another constitutes proof is not at all obvious. And cancer patients are desperate for anything that will help. This is just to say, be careful and check everything you put into your body with your oncologist.
Thank you for educating us!