Monday, Jan 5, 2009 3:39 PM UTC

Dear medical community, WTF?

Obese cancer patients given too little chemo don't survive as long as those given an appropriate dose. You don't say.

I am not a doctor, or anything close to it. But if you asked me, as a layperson with a modicum of common sense, whether to base a medication dosage on a person’s actual weight or her “ideal” weight, I’d have to go with actual. It seems more logical to administer an amount likely to work on the person requiring it, rather than on an imaginary thinner version of her, no?

Well, there I go showing my lack of medical training. Says Dr. Kellie Matthews, an OB/GYN at the University of Alabama at Birmingham, “Often chemotherapy dosing is calculated using ideal body weight as a guide.” So it follows that the farther you are above your “ideal” weight, the greater your chances of receiving an inadequate dose of chemo.

Matthews recently headed up a study that bore this out. Based on the records of more than 300 patients who suffered from an aggressive form of ovarian cancer, she determined “that when actual body weight was used in chemotherapy dosing the overall survival was 40 months for non-obese patients and 47 months for obese patients — statistically identical rates when considering the relatively small size of the study.” However, “[e]arlier studies had found that obese women with ovarian cancer were likely to have shorter survival times than non-obese patients with a similar type and stage of ovarian cancer.” So, when a fat woman is given a dose of chemo appropriate for a thin woman, it turns out she’s less likely to survive as long as a woman given an appropriate dose for her size. When she’s given a dose that takes her weight into account, the difference essentially disappears. You don’t say!

I can’t begin to express how furious this makes me, not only because you have to wonder how many larger women died prematurely due to inadequate doses of chemo, but because until now, the lesson taken from that was that the obesity itself reduces one’s chances of survival — placing the blame squarely on the patients. Yes, as the article points out, obesity is associated with greater difficulty in recovering from any surgery, but as the study demonstrates, that doesn’t necessarily affect mortality rates. Undermedicating patients, however, apparently does. How on earth did it take this long to figure that out?