Learn about the differences between maximum tolerated dose chemotherapy and metronomic chemotherapy for treating your dog's cancer.
James Jacobson: When you’re using chemotherapy for your dog’s cancer, there are different ways of giving it at different amount that deals with metronomic chemotherapy versus maximum tolerated dose. Do we have that right Dr. Dressler?
Dr. Demian Dressler: That’s exactly right and the traditional or conventional way of delivering chemotherapy is to give as much as possible, as frequently as possible, and we say maximum tolerated dose. Tolerated means how much can the pet’s body withstand before having side effects are unacceptable. Like serious organ failure or worst case scenario scary things like death. So these doses have been work out in such way that we give as much chemotherapy drug as possible and minimize the odds of these very very high impacts side effects, and that’s maximum tolerated dose. Now, we will see higher rates of side effects and sometimes serious side effects in comparison to other therapies or other treatments in different areas of other medicines. So for example an antibiotic or hormone therapy, or something else. It’s true that in the area of chemotherapy I’m not trying to scare everybody, but the area chemotherapy we do have higher side effect rates. Now, we contrast these maximum tolerated dose method with something called metronomic chemotherapy, and with metronomic therapy what we’re doing is we’re giving a much much lower dose and the design of that treatment method is to help to supress the cancer, spread to limit its growth and to improve our longevity.
James Jacobson: Dr. Ettinger, your thoughts on this subject.
Dr. Susan Ettinger: Yes! With the maximum tolerated dose in most of our dog patients that those limiting toxicity is the white blood cells. So, when you’re giving this high dose chemotherapy, you are trying to kill rapidly dividing cells in typically those of the cancer cells and you’re trying to kill those cancer cells directly. White blood cells are also rapidly dividing. That’s usually where you got to the top dose you can give to a dog. With the metronomic just as Dr. Dressler said, you were giving a much lower dose of chemotherapy usually with no interval, no break between the chemotherapy. So when you’re doing maximum tolerated dose, your dog will get chemotherapy once a week or every other week or maybe in every three weeks. When you’re doing low dose oral chemotherapy or metronomic chemotherapy, your pets gonna be getting probably some oral anti-cancer therapy everyday of the week or at least every other day. So again, there’s a very little break. Instead of targeting the cancer cells directly, you actually targeting the blood vessels that feed those cancers and allow them to get bigger than about a centimeter which is about the size of most people’s thumb now. So, if you can target those blood vessels, those cancer cells can’t get nutrients, they can’t get blood supply and they’re not gonna get bigger. Again that is called antigiogenesis, and that’s the goal of metronomic chemotherapy.
James Jacobson: Do you see that being use with increasing frequency?
Dr. Susan Ettinger: I do, but I don’t think that every cancer is gonna benefit from metronomic chemotherapy. We’re definitely seeing a role for it for dogs that already have metastasis or cancer that has spread and that’s the big place where we’re using metronomic chemotherapy. Probably the number one place that I’m using it in my patients. For those dogs that they come in and they’re cancers spread in general maximum tolerated dose chemotherapy doesn’t help them very much and we can drive our course of metronomic chemotherapy. I’m seeing really some amazing results when dogs at metronomic therapy. I have dogs where I would have guessed that they would have live to only one or two months with cancer spread and with this metronomic approach. I am seeing some dogs that are out 8 months to 10 1/2 months, over a year and there on this drug chronically and they tolerate it really really well with good guidance.
James Jacobson: So, a lot is not necessarily better than a little and I think this applies to lots of things in life.
Dr. Demian Dressler: There’s an interesting little side note to this out in mother nature, there are natural compounds that have in test tubes and petri dishes in the molecular biology compartment, a lot of the effects that the pharmaceuticals have in attacking those enzymes and those molecular machinery that impacts the blood vessels. There are certain things out in nature that have some similar effects and we do talk about those in the book.
James Jacobson: A lot of information more than we can cover in this video is in The Dog Cancer Survival Guide. Dr. Dressler in Hawaii, Dr. Ettinger in New York. Thanks so much for being with us.
Dr. Demian Dressler & Dr. Susan Ettinger: Thank You!
Did You Find This Helpful? Share It with Your Pack!
Use the buttons to share what you learned on social media, download a PDF, print this out, or email it to your veterinarian.