Another Choice in Palliative Care of Osteosarcoma
In April of 2013, I noticed my 7 year old bitch, Neesha, had a slight lameness in her right foreleg. Radiographs were taken and the results were clear. She had a bone tumor in the carpus area. A friend of mine had recently had a young dog diagnosed as well and had very good results with palliative radiation combined with oral chemotherapy. I contacted Washington State University’s School of Veterinary Medicine and made an appointment for Neesha. Jeanean Fidel, DVM met me and discussed the combination therapy.
In this protocol, the radiation is a higher dose than used in the past. After a full work up to evaluate blood chemistries and general health, the dog is scheduled for a brief anesthetic with propofol for the initial radiation treatment. The same procedure is repeated 24 hours later. The cost of the 2 doses of radiation with the veterinary college was approximately $400.00. Radiation through a private veterinary hospital in the Seattle area would have been considerably more expensive.
The chemotherapy protocol utilizes the drug lomustine in what is called a metronomic dose. Metronomic chemotherapy is a low dose at high frequency that lowers toxicity and is aimed at the tumor. It was a simple regimen with just one oral pill per day. The dose is carefully calculated from body weight and mass. It was formulated at RoadRunner Pharmacy in Arizona and cost about 65.00 a month. Regular blood work is used to monitor organ function for any signs of toxicity.
About 5 days after her first radiation, Neesha no longer washed the affected leg and showed no limp at all at the walk. When she was running, she was still leading with the other foreleg in the canter. In 10 days, she was running completely pain free. She had a normal gait at walk, trot and gallop. And gallop she did!! One of the side effects of radiation is that the bone strength can weaken, so fracture can still be a concern.
After approximately five months symptom free, she developed a slight limp. We chose to do another treatment series. She bounced back even faster and had another 4 1/2 months without pain. At about the 12 month mark, she developed pain in the leg again, so we did an x-ray to evaluate the appearance of the bone for strength. We did another radiation series at WSU, but this time, she did not respond to the treatment. In only 10 days or so, we knew that we had to make the toughest choice to let her go.
In my 30 years in Wolfhounds, I have experienced several dogs with bone cancer. I have used many different strategies, but I have never seen such a remarkable lack of pain without amputation. Truly, Neesha had no idea for that year after her first treatment that anything was wrong. No side effects. I know it doesn’t work for every dog that they treat, but if even one family gets a similar effect with their dog, it is worth it!
I contacted 3 Irish Wolfhound owners who have used this same protocol in the past few years. Each of them have had a varying length of pain free time with their Wolfhound, but all would go to this therapy again without question. All had positive diagnosis of osteosarcoma. I think it is important to stress that NOT ALL DOGS respond to palliative radiation. But in my personal experience, it would be well worth trying.
Here is a summary of our experiences:
Neesha - 7 year old spayed female Osteosarcoma: Right radius
Treatment: Radiation: Two 8 gray (Gy) fractions given 24 hours apart. Lomustine treatment (1 oral pill per day) started 2 weeks later.
Other meds: Meloxicam 7.5 mg daily
Response: No lameness within 5 days.
Relapse: 5 months pain free, mild lameness returned.
Treatment: Repeated radiation treatment and maintained lomustine chemotherapy.
Response: No lameness within 7 days
Relapse: 4.5 months pain free, moderate lameness returned.
Treatment: Repeated radiation treatment and maintained lomustine chemotherapy
Response: No response to treatment. Pain increased significantly over 10 days. Euthanized due to lack of pain control.
Summary: Almost 10 months of symptom free time. No metastasis seen throughout treatment.
Tallann - 5 year old castrated male Osteosarcoma: Left scapula (often has a poorer prognosis than appendicular lesions)
Treatment: radiation same as above Lomustine treatment started 1 week later with blood chemistries every month.
Other meds: Gabapentin orally, Meloxicam orally, Fosamax once a week orally. Tramadol as needed.
Other issues: Tallan also had a torn cruciate ligament in his right rear leg.
Response: No lameness in front after one week.
No relapse. (Note: Fourteen months from the date of diagnosis of the bone tumor, Tallan developed severe pneumonia after an accident. He was euthanized unrelated to the bone tumor.)
Caspian - 4 year old intact male. Osteosarcoma: Right radius tumor --aggressive mixed osteolytic and proliferative lesion.
Treatment: radiation same as above; Lomustine started 1 week later with regular blood work followups.
Other meds: Daily NSAID, Tramadol and Gabapentin for pain as needed. Pamidronate infusion started at WSU with radiation treatment. Monthly pamidronate infusions maintained for the next few months.
Response: Complete lack of symptoms within one week. Active and pain free for four months.
Relapse: In four months, some lameness returned. Small areas of metastasis found on lung x-rays.
Treatment: Repeated radiation treatment and maintained lomustine therapy.
Response: Slight response to radiation, but pain meds were necessary within the month.
Caspian suffered a seizure while on a walk the next month. The seizures repeated the next day and the decision to let him go was made by the owners. Causes of the seizures are unknown, but the pamidronate infusions may have played a role.
Bailey - 9.5 year old spayed female Osteosarcoma: Right radius tumor-- Bailey did not have extreme pain, but the tumor was growing larger and larger.
Treatment: radiation treatment same as above Lomustine started within a week or so. Bailey maintained a good gait and did not show any signs of pain. Regular x-rays were taken to monitor for bone density.
Other meds: none mentioned.
Response: Bailey continued to have little evidence of pain even in face of increasing tumor size. Interestingly, the density of the bone that was not involved in the tumor remained very good. A brace was fashioned for Bailey in order to protect her leg from the large tumor while walking.
Relapse: Bailey’s tumor continued to increase in size. The x-rays about 4 months into treatment showed metastasis to lungs and spleen. However, the tumors in the lungs appeared “encapsulated.”
Treatment: It was decided to do one more radiation treatment.
Response: She continued to do well, active and happy. In about one month, she had a sudden turn for the worse, losing control of her rear end and having difficulty rising or walking. It was decided to euthanize her at that time.
Ellen Kroll may be reached at Kroll.Ellen@gmail.com to discuss this treatment protocol
References:
The 2 dose Radiation Therapy protocol was published in 2009 in the Journal of the American Animal Hospital Association 2009-Jan-Feb; 45 (1):24-32. “An expedited palliative radiation protocol for lytic or proliferative lesions of appendicular bone in dogs.” Knapp-Hoch, HM, Fidel, JL, Sellon, RK, Gavin, PR.
Abstract: Fifty-eight dogs with lytic or proliferative bone lesions were treated with a radiation protocol of two 8-Gy fractions over 2 consecutive days. The protocol was well tolerated, with no increase in early or late effects over previously published protocols. Forty-three (91%) of 47 dogs responded positively to radiation, with a median time of 2 days to onset of pain relief. Median duration of pain relief was 67 days (range 12 to 503 days; mean 99+/-16 days). Median survival time for all dogs was 136 days (mean 179+/-18 days). Distal radial location was a positive prognostic indicator for survival (P=0.005).
The Lomustine protocol has not been published yet, but Dr. Fidel is very open to discussing with veterinarians who may be interested in this treatment option. She can be contacted at WSU College of Veterinary Medicine Pullman, Washington.