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Those powerful drugs kill not only cancer cells but healthy cells as well. And that makes some doctors nervous, so they order chemotherapy doses based on patients’ ideal weight, not their actual weight.
But Griggs knows that such hesitation carries a high price: Up to 40 percent of obese cancer patients don’t get large enough chemotherapy doses, jeopardizing treatment of individual patients -- and the overall public health.
Now, Griggs and her co-authors, writing in the latest issue of the Journal of Clinical Oncology, have published new guidelines aimed at making sure even the heaviest cancer patients get the full treatment they need.
“It looks like we could save up to 6,000 lives in breast cancer a year,” Griggs says, by giving obese patients the right-sized dose.
The guidelines should help resolve confusion among cancer doctors over the correct doses for patients who weigh in at 250, 300, even 400 pounds.
“I get a lot of emails from people who … want to fully dose, and their colleagues are telling them they can’t,” says Griggs, a University of Michigan breast cancer specialist.
The confusion over how much chemo to give obese patients stems in part from the caps research trials used to put on doses, Griggs and her coauthors write.
Take the drug docetaxel, or Taxotere, used to treat breast and lung cancers. The traditional capped dose is 150 milligrams. But for a 400-pound patient, the size-based dose would be 212 milligrams, a significant difference, says Judith Smith, director of pharmacology research at the University of Texas M.D. Anderson Cancer Center in Houston.
Even at that world-renowned institution, some doctors insist on using outdated caps, says Smith, of the department of gynecologic oncology and reproductive medicine.
“The physicians fight me on it,” says Smith, who was not involved in writing the new guidelines. Still, she says, “I don’t fight that battle on a daily basis anymore.”
The authors of the new guidelines acknowledge a scarcity of studies that randomly assigned obese patients to capped doses or size-based doses of chemotherapy drugs.
But, they write, research suggests that obese cancer patients actually do better, not worse, when treated with doses commensurate with their size. They don’t experience any more toxicity with weight-appropriate doses than do lean patients, and they are more likely to be cured than those who are under-dosed.
“You’re not going to harm your patient if you give them the full dose,” Griggs’ co-chair Dr. Gary Lyman, a professor of medicine at the Duke Cancer Institute, tells msnbc.com. “In fact, just the opposite.”
Under-dosing is probably a “significant” contributor to the higher cancer death rates among overweight and obese patients, Lyman says.
Size-based dosing might most benefit breast cancer patients who are black and/or poor, the authors write. No matter what they weigh, breast cancer patients in those groups are more likely to receive reduced doses of chemotherapy, and their higher rates of obesity only compound the problem.
Correct dosing would be a boon even amid an ongoing shortage of cancer drugs, says Lyman, who calls the situation "a travesty." Appropriate dosing of obese patients should have little or not impact on the shortage situation. In most cases, Lyman says, fully dosing obese patients simply means using all of the vial of a drug instead of throwing away part of it.
There are exceptions to the recommendation of full dosing of chemotherapy drugs for obese patients, according to the guidelines. Fixed doses, prescribed independent of a patient’s weight, are justified for a few, such as carboplatin and bleomycin, because of concerns about nerve tissue damage.
The guidelines note that costs, even insurance co-pays, could be higher with larger doses, although, Griggs says, many chemotherapy drugs are off-patent and relatively inexpensive.
And, Lyman says, the cost of treating recurrent cancer or providing palliative care after the disease has spread “probably far outweighs giving the full dose of chemotherapy.”
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Doses are calculated for the required concentration in blood and tissues. If the drug is not fat-soluble, fat should not be taken into account.
Um... it's not that simple.
A. Would you give the same dose to a 70lb. child as to a 170lb. man? Mass does not equal fat.
B. You're thinking high school Chemistry, not Biochem or Pharmacology. Drugs don't necessarily work that way.
The bigger the person, the more blood & fat tissue they have.
Another reason to make gym memberships mandatory!!!!!!!!!
Well, I'm paying for it every month, but still didn't lose any weight...
The sad thing is obesity is a huge risk factor for most cancers.
The statement about fixed dosing of certain drugs needs to be corrected in this article. Vincristine is generally capped in order to avoid neurotoxicity.
Well now, it looks like we've just uncovered one of the REAL reasons why 'obesity' is supposedly responsible for 20% of cancer deaths - as in so many other areas of medicine, larger people don't get the proper dose or the proper treatment.
And making gym memberships mandatory won't solve anything. While exercise has been proven to improve health, it has NOT been proven to significantly affect weight loss in many people. Having a gym membership won't stop anyone from getting cancer if it comes from environmental factors. And a gym membership won't do squat to prevent a thin person from getting cancer [yes, they DO get cancer also, it's not just obese people] as BIG DIET would have us believe.
Please post the study that says exercise does not significantly affect weight loss in most people. Would love to see that.
Having a gym membership may not prevent cancer, but it will ward off obesity, heart disease, weight related diabetes, depression and more. Since heart disease is the #1 killer in the U.S., one study on obese people and cancer does not at all suggest that losing weight is no longer important.
I second this.
How 'bout this one:
http://www.time.com/time/magazine/article/0,9171,1914974,00.html
From the article:
Now, although I do believe that exercise helps in weight loss, the ratio of diet to exercise is something like 80/20. And although the theory proposed in this article has merit, I really think it's more complicated than the article makes it appear.
Exercise stimulates hunger because it kick-starts your metabolism.
The key remains to be, self control. That poster made it seem like exercise is useless. It's not. You just don't go out and eat an entire pizza afterward.
Thanks for sharing.
I think what this guy is saying makes complete sense. Essentially, exercise does facilitate weight loss IF it's paired with a healthy diet. If people want to lose weight, it's an important component to the process - but in order to be successful they can't eat back all of the calories they just burned off.
This is common sense to me.
It's all about practicing self control and learning which foods will make you feel full after a workout without packing a huge caloric punch.
OMG, medical doctors for people are finally starting to get tailoring the dosage to fit the body mass of the patient! It is common sense, yet only your dog or cat got to have meds tailored to body size by the veterinarian. Hey, AMA, what has taken you guys so long to catch up to the doggy docs? It is good for dogs but not people?
Remember that both professions are still just practicing! I cannot wait for the actual event to start! It should be just any day now!!!!!!!
Im nowhere close to being a doctor and even i know that the amount of drug you take is relative to your weight.
here's the problem...when you are actually the one writing prescriptions for these toxins, you tend to get a little skittish when prescribing huge doses
Not only that, but the trials used to put these drugs on the market did not include many patients, if any, of this size. So no one really knows the right dose to use since its never been looked at...
eric, AMEN! So how to we get more data, to calm your nerves, and produce population size that us researchers want to see for ALL patients?
I'm presently going through chemotherapy and I didn't have any other major medical problems when I was diagnosed. My weight was within range, I didn't have high blood pressure or diabetes. I know cancer patients who had these conditions when they were diagnosed and fighting cancer on top of it all is really impacting them. Patients who are obese need to work with the oncology nutritionists on getting a handle on their weight. My doctor told me that if they don't, they stand the risk of ending up un the hospital on a respirator.
When it comes to cancer treatment, size does matter.
Peace.
The problem is these people need to lose weight in a hurry. They've lived their whole lives eating a certain way, many of them 'stress eaters', and now we expect them to completely change their eating habits during one of the most stressful periods of their entire lives. Good luck with that.
The changes should have come 10-20 years before they were ever diagnosed. As a primary care physician, I constantly barrage my 30 and 40 somethings about their weight in the hopes that they finally get the message. Our primary care services in this country are seriously, seriously lacking thanks to our screwed up reimbursement system.
Ditto for surgery. When obese patients have cancer, often they need surgery right away, but they are not eligible for surgery because of their weight — and at that point, there's not enough time for a weight-loss regimen to kick in.
Another reason yet why the 'reform' of our health care system needs to start with looking at our food supply, and our attitudes about food. You can't fix a "fat tire" until you shut off the air pump to the tire.
Now I'm thinking of beer.
The problem is people don't want "the big bad government" telling them what they can and cannot eat, although it's apparent these days that good decisions are in short supply.
Chemo is a poison. It kills the body. The only hope is that the body manages to outlive the cancer. What a ridiculous excuse for a treatment.