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Friday, January 9th, 2009So you’ve probably heard that some studies show obese people have a greater chance of dying from some forms of cancer. Those studies are often cited as evidence that we need more state control over what people eat.
As it turns out, the higher mortality rates may in part be because medical professionals don’t factor in the added weight when dosing obese people with chemotherapy.
You would think that they would be more sensitive to this subject considering the way that a lot of women have complained about how so many measurements used in medicine are biased toward the male body.
Now we need more state control over doctors.
I did work in cancer chemotherapy dosing in graduate school, and dose determination is actually a little more complicated than this. If they are using this ideal weight, then they are probably using that weight to _estimate_ body surface area (BSA). Chemotherapeutics are commonly dosed based on the patients BSA. But it gets worse…
Methods for estimating BSA were derived in the early part of the last century. These correlations were based on covering a relatively small number of people with paper (I don’t remember the exact number but I’m pretty sure it was less than 100), calculating the area of the paper and correlating the area of the paper to parameters like height and weight.
It is very complicate. some medications distribute in the fat and some do not. So the extra fat, may or may not make a difference. Point is, everyone, if treated properly for any medical problem, has to be treated as an individual. One cannot practice “cook book” medicine and expect good results. I know in pain management, most are under-dosed because of government watchdogs.
Bottom line, patients appreciate a doctor who will listen and discuss care with the patients. They feel someone is actually listening and not rushing off into the next room! Taking your time does not seem to be a realistic virtue of a lot of physicians, now-a-days!
I should also add, obese patients with tumors often have them discovered later, because the tumors are not as readily detected. This can result in a stage 3 breast tumor being discovered instead of a stage 2, in a large pendulous breast. An ovarian tumor would obviously be detected later in a woman with a bigger abdominal girth. There are so many factors that influence the death rate from cancer, it would be impossible to relate under-dosing chemotherapy as the difference, alone, in those death rates. And lets remember. It is poison you are giving that patient. Just enough to kill the cancer, but not the patient!
Medical proclamations are like clothing trends. They’re designed to become unfashionable to make room for new styles. Today’s healthy living recommendations will ultimately be declared the causes for tomorrow’s ailments.
It’s a good thing Radley is making his medical proclamations based on an article entitled, “Dear medical community, WTF?”
Always smart to base your opinions on one individual study, too. Because individual studies are never prone to either Type I or Type II error, depending on their design…..particularly ones that apparently were retrospective in design.
“statistically identical rates when considering the relatively small size of the study” Hmmm. Why might this be important.
The funny thing is, if this same study had suggested that higher dosages of chemotherapy resulted in higher rates of opportunistic infections, anemia, leukopenia, thrombocytopenia, neuropathy, etc. in the obese resulting in excess mortality, the same authors would be labeling their articles “WTF medical community? Why are you trying to kill fat people?!?!?!?”
Let me echo John And Michael’s points that dosing is not that simple. Dose-response relationships for lots of things (esp anesthetics) get really non-linear and difficult to extrapolate in people (or animals) with lots of adipose tissue.
There is also mounting evidence (mostly in animal models, so a long way from clinical work) that the chronic inflammation associated with metabolic syndrome leads to dysregulation of multidrug resistance transporters and associated transformation enzymes, which makes this an even thornier issue.
If the poster in the link wants to know why it takes so long to figure all of these things out, much less translate these findings into better clinical practice, she should talk to the FDA…
(Disclosure: I am a basic scientist, not a physician.)
Mike T,
Can you give a few examples of male-bias measurements?
The problem with looking at higher dosings for chemotherapy drugs is that the toxic side effects often make it too dangerous to the patient in the short term to use those dosings.
[...] and effect again. Do obese people have worse cancer treatment outcomes because they are obese….or because they are not treated [...]