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Question for Dr Lee , chemo

July 23rd, 2007, 08:20 PM
Hi Dr Lee, I was wondering about chemo for dogs , I had an older golden with mast cells cancer (had 2 operations) and decided against chemo. Franctly , I don't believe it makes things better for the animal. See , what I don't get is why humans need chemo mixt with radiation for the treatment to work. I only know one person who's vet told him his dog needed both. The other vets just tell their customers their dogs need chemo , never talk about radiation. So how can chemo only , is suppose to cure cancer for a dog , without the radiation ? :confused:


July 23rd, 2007, 08:29 PM
It's a question for Dr Lee , but others can share toughts / experiences / opinions too . Please do !

Dr Lee
July 24th, 2007, 06:15 PM
I am sorry about your golden retriever mast cell tumors are so difficult. We lost a dog with a grade III MCT.

Why don't vets recommend radiation?
We do, but it may not always be apparent. Whenever a regular veterinarian has recommended referral to an oncologist, we are under the understanding that if the patient is going to be helped by radiation that the oncologist will be the one discussing it with the clients. Also many times the patient is not a candidate for radiation. Why? Tumor type, tumor location, grade of tumor, etcÖ

Each cancer is different and responds differently to treatment. There are three main modalities of cancer treatment: 1) surgical, 2) radiation and 3) chemotherapy. (There are a few others but these are the basic ones.) Often cancer treatment involves more than one of these options. The problem with radiation is that many tumors don't respond to it and it has to do with location - the radiation kills everything in its path therefore an intraabdominal tumor is often a poor candidate due to the surrounding organs. (There is a new technique that utilizes multiple, in some cases many dozens, of low level radiation beams which cross just at the tumor site and thus selectively kill the tumor. This is used in some non operatable brain tumor cases. This rarely an option for pets due to cost.)

Chemotherapy also needs to be understood to be a broad category of medications, which can in some cases just be something as simple as just prednisone. Some tumors respond to vincristine, others to doxorubicin, others to something else. It depends upon tumor type, grade, location, etc... Usually multiple agents are combined.

When I get a histopathology back, which is not benign, I virtually always consult with an oncologist (thankfully most reference laboratories provide this as a free (or at least included) service with the testing). Oncology is rapidly advancing and what is used to diagnose or treat a particular cancer changes often. Sometimes, not just type but location can drastically change a case - for example: Hemangiosarcoma average survival times are: abdomen: 3 months, subcutaneous 6 months, muscle 1 year and skin >2 years on rough estimation. This also changes as to the exact location of the tumor, which organs are affected, has it spread, how big, etc... Each of these cases, even though it is the same type of cancer, has different treatment recommendations as far as: surgery alone, surgery plus chemo, different chemotherapy types, and or whether radiation would also be of benefit or not as a sole therapy or part of a multimodality therapy. We have such a wide range of treatment options and prognosis and we haven't even left one type of cancer yet! This doesn't begin to involve what and how to do with lymphosarcoma, MCT, fibrosarcoma, melanoma, pheochromocytoma, spindle cell tumors, osteosarcoma, myoblastoma, schwannoma, leiomyosarcoma, myeloma, neuroma, neurofibroma, etc....

Based upon my consult with the oncologist, I can make a decision on whether the surgery alone was needed or if referral to a nearby oncologist is recommended. If referral to an oncologist is not pursued, anything like radiation therapy becomes irrelevant. Sometimes, based upon the tumor type, radiation is the only option for the patient. In those cases then the regular veterinarian will make a recommendation for direct radiation referral; which of course involves a specialist.

For anyone who is reading this, who hasnít gotten tired of my blabbing, I think the take home message is that every cancer patient is unique with a slightly different prognosis, treatment options (be they surgical, chemotherapy, radiation, or other), response to treatment and monitoring protocols. Furthermore the choice to pursue any or all treatment options with regard to cancer in your pet is a personal choice that should be made after a lot of information gathering from your veterinarian, the oncologists they work with and any other reputable source that you have (e.g. this website). The final decision, when made in the petís best interest, will always be right no matter what that choice may be.

I hope this has answered the questions that you have asked. Let me know if there is anything else that I can help with.

July 24th, 2007, 06:21 PM
Thanks Dr. Lee ! I was reading this last night ~ sort of a primer website for those of us who know little to nada about animal cancer care

but your answer is much more comprehensive.

July 24th, 2007, 08:14 PM
Thank you so much for your reply. I will actually print it tomorrow at work (don't have a printer here) Because I actually understood it all (me being french....) it doesn't change the way I feel about it , but it does help to know all the options. Thanks again !

Dr Lee
July 25th, 2007, 01:27 PM

Many people have various thoughts and feelings with chemo. And with mast cell tumors, chemotherapy may not have been the best option for you and your pet. One of our dogs died from a mast cell tumor and the chemotherapy that we did - I honestly do not know if it extended his life at all. He lived 6 months after diagnosis. I felt okay with the outcome because he handled the medication well and he went hiking up in the mountains up to two weeks before I euthanized him. So I felt his quality of life was good; but in this situation, I don't know that chemo made a difference. Due to the type, grade and location of the cancer, I also knew those odds going into it.

My key point that I hope everyone takes away is that to use or not to use chemo is not a black and white issue. It is only when we make blanket statements such as "I would never do chemo for my pet" or "I would always do chemo for my pet" - that the mistake lies. Once we evaluate the tumor type, grade, location, and the health and emotional status of the patient then we as owners can make a decisive answer for the family.

Also I would like to point out the success stories. There are the Lance Armstrongs of the dog and cat world. Without the chemo, Lance would not be here and I know many pets who can bark or meow the same thing! No it isn't for every pet; but for some it can be a extension of life. And for the record, there are many situations that I have recommended against either chemotherapy, radiation or any other treatments based on the pet.

My goal was not to change your mind on your pet; just to open your opinion if there are any situations that chemo/radiation/etc is recommended in the future. Another pet of mine went through chemo and is doing well. But before I started chemo and during the first few weeks my emotions overran my 'doctor brain' because of the other dog which had died from the MCT. I intellectually thought my pet would do well but emotionally 'i felt it was going to be a waste of time'. The first pet I mentioned - chemo probably did little to nothing; the second one - absolutely saved her life and was why she was able to snuggle up to me this morning!

July 28th, 2007, 05:23 PM
Thank you Dr. Lee, this thread has been very helpful.

I have a question about prednisone. My dog is to start a week of prednisone to see if a low level that appeared on his blood test (not sure which one) will go up before considering chemo. I am wondering about the side effects. Griffey has a very sensitive stomach which my vet is well aware of and has a low tolerance for all oral medications, even the ones that are not supposed to cause stomach upset (such as the levothyroxine (sp ?) for his hypothyroid)

My vet is away until Monday and I was supposed to start him on the prednisone. He recommended pepcid ac for his stomach a few days beforehand as his stomach has been bothering him since his biopsy operation on Monday (eating grass, vomitting, dark diarhea) I am assuming from the tramadol. His stomach problem is not a new problem or more severe than what usually happens when he has to take oral medications.

The problem is, it is Saturday and his stomach is still not getting better. I stopped the tramadol and the pepcid isn't helping any. He is still eating and drinking water though.

Will the prednisone cause stomach upset? Is the prednisone more important right now than his stomach? My vet in the past did say I could give him other stomach products like Pepto Bismo but before he left, told me some meds will conflict with the prednisone (I was told not to give him any of his arthritis anti inflammatories as it would conflict). Would Pepto conflict?

Sorry for the long winded question. I don't know what I should do. His stomach is really hurting him but also, his glands look like they are getting bigger evey minute so I don't want to wait too long and Monday seems too far away. There is an emergency vet hospital in another city close by that I could take him to if need be.

Thank you very much for your time and any suggestions you may have!

Dr Lee
July 28th, 2007, 05:48 PM
As far as whether you should go ahead with the prednisone or not with regard to the stomach issues; I am going to have to defer to your regular veterinarian. I am sorry I can't answer that one.

As far as the medications being used, hopefully I can answer some of your questions.

Drug interactions with prednisone: NSAIDs (arthritis meds like aspirin, rimadyl, metacam, etc..) DO INTERACT - or that is, they both increase stomach acidity and can decrease mucosal support. The pepcid is fine to give with the prednisone as it helps reduce stomach acidity. Tramadol should also be fine with the medications however with upset stomachs, any medication we add can cause upset.

Perhaps also ask your vet about sucralfate (carafate) - it helps coat and protect the stomach. It often is given at a different time than other medications since there is some questions as to whether it interacts with other drug absorption.

Another thought would be to ask your vet about reglan (metoclopramide) which is an antiemetic (antivomititing) drug.

Often for high stomach sensitivities, I will recommend the pepcid and/or reglan45 minutes or so before other medications so they will be in full effect at the time of medication.

I hope this helps, sorry I could not give you a definitive answer on the prednisone. :pawprint:

July 28th, 2007, 07:08 PM
Thank you Dr. Lee, your reply really does help! It is helpful to know that prednisone can increase stomach acidity something I didn't know. I will keep giving him the pepcid as directed by my vet as I had also stopped this thinking it may have caused the vomitting and will ask about sucralfate and the other ones you have talked about on Monday when he gets back. I was told I could stop the tramadol once his pain was resolved which it has so gave him his last dose last night and hopefully with the pepcid as the only pill to give him, he will be well enough to start the prednisone tomorrow. If not, I will wait until Monday when I can try something else for his stomach. I had already decided not to give him the prednisone today and feel comfortable with this decision. If I have an emergency, will take him immediately to the emergency clinic. Thank you again!