Chemotherapy for Osteosarcoma
Sue Ettinger, DVM. Dip. ACVIM (Oncology). Dr. Sue is a boarded veterinary medical cancer specialist. As a Diplomate of the American College of Veterinary Internal Medicine (Oncology), she is one of approximately 400 board-certified veterinary specialists in medical oncology in North America. She is a book author, radio co-host, and an advocate of early cancer detection and raising cancer awareness. Along with Dr. Demian Dressler, Dr. Sue is the co-author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity.
Updated: October 10th, 2018
How do we utilize chemotherapy to fight osteosarcoma?
In my last two posts about osteosarcoma (OSA), we discussed treatments that address the tumor affecting the bone. We discussed amputation, Stereotactic RadioSurgery (SRS) like Cyberknife, palliative radiation, and limb-spare surgery.
While these treatments are important for the malignant tumor destroying the bone, metastasis (cancer spread) is inevitable. So even if the primary tumor is successfully removed with surgery or killed with SRS, these tiny metastases (which are often undetectable at first) will grow and eventually kill dogs with OSA. This makes systemic treatments aimed at controlling micrometastasis a critical part of conventional care.
Chemotherapy Delays Metastasis
I know what you are thinking: chemo for your dog sounds scary and crazy. But overall chemo in dogs is very well tolerated, with minimal side effects. It’s one of the things I like about my job! Hospitalization from chemo-induced side effects is rare. I have a whole series of blogs dedicated to chemotherapy and its side effects, so if you haven’t read them, check them out. The pet Guardians of my patients are always amazed how healthy and happy their pets are during and after chemo.
I bring this up again because chemotherapy is very effective for OSA to delay metastasis. When compared to treating with amputation alone, chemo more than doubles median survival times:
- Survival times for OSA cases with amputation and no other treatment have a median survival time of four to five months, with 90-100% dying by one year, and only 2% still alive at two years.
- Median survival times for OSA cases with amputation and chemotherapy increase to ten to twelve months, with 20-25% of dogs are still alive at two years.
For me and many of my patients, those odds make chemotherapy a no-brainer.
Which Chemotherapy Protocol Works Best?
The most common chemotherapy drugs are doxorubicin, carboplatin, and cisplatin, which you can read about more in the Guide. The published protocols vary on which drugs to use, how frequent treatments should be, and the number of treatments. Consulting with an experienced oncologist who can look at your dog’s own case and weigh all the options that would work best for him or her is your best bet.
At my recent annual Vet Cancer Society conference in the fall of 2012, there was a great abstract from the group at Colorado State University which looked at almost 500 dogs to compare protocols. Dogs either received doxorubicin, carboplatin, or a protocol that alternated the two. Based on this preliminary report, there were no significant differences in the protocols when measuring how long the patients remained tumor-free, and survival times. As always the case with research abstracts, we will need to wait for the published protocol to come out, but at this point, one protocol does not appear to be better than the other. So discuss the different drugs with your oncologist, with regards to your dog’s specific needs.
Doxorubicin and CyberKnife or Stereotactic Radiation Surgery
A word about using chemotherapy with CyberKnife treatments: for my CyberKnife cases, we don’t use doxorubicin. We avoid this specific drug in cases that have received SRS, because there is a side effect called radiation-recall. This chemotherapy protocol, when given after radiation, can bring back or “recall” some of the early skin side effects that you normally see in the first few weeks after radiation – skin side effects such as redness and burning. (You may hear your oncologist call this “moist desquamation.”) If a dog receives doxorubicin, even months later, those skin side effects can recur. So I never use doxorubicin after CyberKnife, and instead use carboplatin.
Chemotherapy Timing
The best time to start chemotherapy is soon after surgery or radiation, before metastasis has been detected. I typically start chemo about two weeks after surgery or SRS.
Bottom Line: You Have Time
While a diagnosis of OSA may be very scary, it is not an immediate death sentence. As you’ve seen, there is a wide variety of treatment options. As always, I encourage you to consult with an oncologist and discuss the pros and cons, based on your dog’s underlying health, the extent of the disease at diagnosis, and your budget.
All the Best
Dr. Sue
Sue Ettinger, DVM. Dip. ACVIM (Oncology). Dr. Sue is a boarded veterinary medical cancer specialist. As a Diplomate of the American College of Veterinary Internal Medicine (Oncology), she is one of approximately 400 board-certified veterinary specialists in medical oncology in North America. She is a book author, radio co-host, and an advocate of early cancer detection and raising cancer awareness. Along with Dr. Demian Dressler, Dr. Sue is the co-author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity.
So glad i read your post about not using doxo with cyberknife. If cyberknife was done feb of last year, I assume u still dont use it?
Our 7 yo Cavalier King Charles was diagnosed with osteosarcoma of right posterior stifle in late Oct .2013 . She has her limb amputated and we began carboplatin with pamidronate therapy 2 weeks later . She has done beautifully , hardly missing a beat . She has no radiographic evidence of disease on her chest films and is otherwise completely healthy- a rare find in this age Cavalier.
I hate speculation, but often wonder how long we have with her … We have her on Immunity tabs , Apocaps etc… Is there anything else we can / should be doing to help her in this fight ? Thank you ,
Our dachshund mix had her front leg amputated within weeks of her osteosarcoma diagnosis. Because statistics indicated that expensive chemo treatments would not lengthen her survival time significantly, we opted to not have chemo. It is now a year and a half post-amputation. She has digital chest x-rays every 6 months, and no metastases has been detected. Is there a usual time frame in which metastases occurs? Is there ever a point at which we can assume or say she beat the odds and micro-metastases did not occur?
Our Old English Sheepdog was diagnosed with osteosarcoma the day after Christmas. Her right front leg was amputated the next day. Bella has had 5 of 6 carboplatin treatments. Our vet provided us with information regarding a study that produced results of the median survival rate for 6 treatments is 535 days vs 307 days for 4 treatments. (www.vetcancerspecialists.com) Search on ostesarcoma then “What about chemotherapy for osteosarcoma?” Bella has done amazing with the chemo. No side affects. This study helped us make an informed decision, along with the information on this blog.
If one of my dogs was diagnosed with this, I don’t think it would be worth putting them through all of that, amputation, chemo etc, just for an extra 12 months. I would love to see more research being done and records being kept by vets of cancer patients’ details (perhaps this is already being done in the US?). In the future, I have no doubt that survival times will be extended and prevention will come to the fore.
Geat work Dr Sue – all the best!
Dr. Sue, thanks so much for this fantastic information. As always, you provide a great resource for our community.
When the CSU findings about protocols is published, can you please update us on those?
Thank you so much for all you do.