As told by Stan Stearns
When I learned that Gabriel had bone cancer, I wasn't ready to accept the prognosis of "amputation, then he might have a year." As I began searching the internet for any information I could find about promising research, I found an article about a clinical trial at Colorado State University Animal Cancer Center which explores a new method for delivering samarium (Sm 153 lexidronam, Quadramet®) that avoids the systemic or whole body side effects. The method involves isolating the blood supply to the affected limb and delivering a dose of the drug directly to the tumor. This sounded like a good possibility, particularly if it could be augmented with other treatments I had been learning about, such as chemotherapy with Cisplatin or Carboplatin and administration of antiangeogenesis inhibitors and zoledronate, an amino-bisphosphonate.
After a 20+ hour drive from our home in Gig Harbor, Washington to Colorado State University's Animal Cancer Center, a Tc99M bone scan done by Dr Phillip Steyn confirmed the MRI diagnosis done by Dr. Par Gavin of Washington State University School of Veterinary Medicine. Gabriel had osteosarcoma of the right distal tibia. Dr. Bill Dernell confirmed that OS of the distal tibia was inoperable if proper function of the leg was to be realized.
I asked Dr. Dernell if he would consider adding the other elements of treatment to Sm-153 EDTMP called for in the clinical trial, all without amputating Gabe's leg. To my great relief, he agreed to this plan. However, since this would be outside the defined trial, I would have to pay for the radioisotope (sm-153). He also suggested the use of external radiation to augment the treatment of the tumor.
After Gabriel was treated, I learned that limb isolation was not used because problems with the arterial cannula were not conducive to long term viability of his leg. The dogs in the study were to have their legs amputated three weeks after receiving the Sm-153. My initial depression after hearing this stimulated me to start thinking about how products and techniques developed at VICI might contribute to an alternative means of concentrating radiochemical therapy with less vascular involvement. Since then, promising strides have been made in developing tools for the targeted delivery of therapeutic agents to primary osteosarcoma sites and bone metastases. See <Current projects>.
By June it was clear that we had lost control of the primary tumor in Gabe's rear leg. The leg was quite swollen and was nothing but a useless burden to him. In a search to find a veterinary oncology center closer than the excellent UC Davis Veterinary School, we discovered that the young veterinary program at Oregon State University has attracted some world class faculty, including the new veterinary school dean, Dr. Cyril Clarke DVM, PhD dipl. ACVCP; Dr. Stuart Helfand, DVM dipl ACVIM (oncology), who is currently treating Gabriel; and Dr. Bernard Seguin, DVM dipl. ACVS surgical oncology, the brilliant veterinary surgeon who performed the amputation of Gabriel's cancerous leg. Ironically, I learned only at this point in the progress of Gabe's disease that Dr. Seguin has been successful in resecting a distal tibial osteosarcoma without loss of joint function.
Gabe recovered quickly, and had a great time during our family Christmas in Alta cavorting in the snow like a puppy. The loss of 40% of his lung volume and being in the thin air at 8500 feet seemed to have virtually no effect.
On the trip back to Gig Harbor, we stopped in the Portland area for a follow up CT scan at VDIC, an exceptionally well-equipped veterinary imaging center. The scan revealed that the disease had progressed, with mets in the caudal lobe of the left lung and most disturbing of all a 1 cm lesion in the cranial lobe of the right lung. On Monday, Dr. Seguin will remove the caudal lobe of the left lung. Hopefully the inhalation therapy will keep the disease in check until the last lesion can be removed.
I still believe that the inhalation therapy is a valuable treatment, but we have more to learn about how to administer it. For example, the prevalence of metastic activity in the lower portion of the lungs would seem to indicate that simple inhalation does not distribute the agent over the entire lung area; gravity is required to make sure it reaches the caudal lobes. Gabe now has to sit through the entire treatment, instead of lying down.
Plus, I suspect that the equipment setup doesn't function well in an environment with low relative humidity. We noticed while we were in Alta that the nebulizer was not producing the cloud of vapor that is usually evident. With the usual 20-20 hindsight, I can guess that the water was probably simply evaporating instead of nebulizing, and can see that it probably would have helped to use a vaporizer or humidifier in conjunction with the nebulizer. Unfortunately, that period of less effective treatment gave the disease a chance to get a better foothold in Gabe's lungs.
So the setback is discouraging, to say the least. But here we are a year after the initial diagnosis of bone cancer, and we still have a happy, active dog who continues to be a trooper through the entire process.
January 17, 2008