Ironically, while cancer may be the leading cause of death in geriatric dogs, it is also the most treatable disease, when compared with congestive heart failure, renal failure, and diabetes mellitus. Which was probably why our oncologist, Dr. Beth Overley, was optimistic about Bentleys prognosis. Lymphosarcoma, a cancer of the lymphocytes (a type of blood cell), and lymphoid tissues, is the third most common cancer diagnosed in dogs and, as she put it, is the best one to get. And while Bentley was certainly sick, she wouldnt know how sick he was until they performed a series of tests to search for tumors in other locations.
Given how enlarged his lymph nodes were, she recommended that we leave Bentley at the hospital for the rest of the day for staging and, pending the results, his first course of chemotherapy. Encouraged by the first optimistic news we had heard in a month, we left Bentley in what we knew were some of the most capable and compassionate hands we had ever encountered. As sick as he was, he wagged his tail and eagerly followed Dr. Overley as if he knew she might be able to help him.
Staging helps us evaluate the stage of the disease and helps monitor its progression, Sorenmo explains. It can also help influence an owners decision to treat the animal. We know a lot about the biological behavior of tumors, and radiographs and ultrasounds of the lung and abdomen are extremely informative. In addition to chest x-rays and an abdominal sonogram, Bentley would undergo a complete blood count, a serum chemistry profile and urinalysis as well as a bone marrow aspirate.
By the end of the day, we had the results. Bentleys official diagnosis was stage Vb Lymphosarcoma. The cancer was present in his lymph nodes, some abdominal organs, and his bone marrow. The good news was that his chest x-ray did not show any evidence of either a mass or metastasis, but there was no denying that Bentley had advanced stage disease. He also had a significant infection at the site of his incision.
In spite of what sounded, to me, like a fairly bleak prognosis, Dr. Overley remained hopeful and encouraged us to treat our dog. Lymphosarcoma, she told me, is incredibly sensitive to chemotherapy, and up to 80 percent of dogs treated go into remission. The length of the remission will vary from pet to pet, but for those dogs that have the most common type (lymph-node enlargement), the average remission time is usually around 8-10 months with an overall survival time of about one year. From where Bentley was right now, one year sounded awfully good.
She explained that there were essentially two chemotherapy options, a long and a short protocol. The difference is the amount of time (1.5 years versus 22 weeks) and the toxicity of the treatment. The long protocol involves treating the animal once a week for 4-6 months, then restaging; if all is clean, the dog is treated every other week for another 4-6 months. If still clean, another treatment resumes every third week, for 4-6 months. At that point, if everything is still clean, the treatment is discontinued.
The short protocol uses two drugs per week for 22 weeks, and then stops. It involves less time and money, but it carries an increased risk of toxicity.
She told me that in her experience, side effects are seen in less than 5-7 percent of dogs and range from gastrointestinal disturbances to infection associated with a low white blood-cell count. In a recent Penn study examining owners impressions of their pets quality of life while undergoing chemotherapy, the dogs treated at Penn were given an 8 on a scale of 1-10, with 10 being the highest. Most owners claim that their dogs are the same as ever, and some even say they are better than they have ever been.
There was no way of knowing, of course, how Bentley would respond to the treatment, but the most common side effects include nausea and vomiting, both of which could be controlled with medication. Overley did not think he would lose his hair, although the growth might be slowed, and she recommended that we proceed immediately with the short protocol. By the time I picked Bentley up later that afternoon, he had already received his first chemo treatment.
Sporting a new bikini cut courtesy of the ultrasound, Bentley was delighted to see us and seemed none the worse for wear. I was sent home with what seemed like an entire pharmacy: two antibiotics for his infection, anti-nausea drugs in case we needed them, a steroid to be given for one month in gradually decreasing doses, and samples of dog food for cancer patients. We have found that tumors dont grow as quickly on a high-fat diet, Overley explained as she went over my instructions for the week. She repeated her optimistic projections. Usually we see a decrease in size in the lymph nodes within 24-48 hours, she said, showing me how to palpate his glands. Promising to check in with us in a day, she sent us on our way.
Later that night, when I tentatively felt Bentleys glands, they did indeed seem smaller to me, but I thought I was imagining things. The next morning they had all but disappeared. When Bentley eagerly gobbled down his new dog food, the first dog food he had eaten in weeks, I allowed myself to share some of Dr. Overleys optimism. Maybe this wasnt going to be so bad after all.
Bentleys chemotherapy regime consisted of a four-week induction cycle, with one week of rest, repeated three times, followed by seven weeks of every-other week treatment. He made it through all 22 weeks with remarkably few side effects; in fact he seemed to feel better than he had felt in a long time. He had occasional gastrointestinal issues, which we controlled with medication; his hair did not completely grow in from his first ultrasound, and he lost some weight. But, looking at him, it was hard to believe he was actually sick. He was alert, playful, energetic, and actually seemed to love to go on our weekly outings to Penn, where they treated him like a visiting dignitary. Each treatment took about two hours, and I was able to drop him off and pick him up at my convenience.
Quality of life, a term I heard repeatedly during Bentleys sojourn at Ryan Veterinary Hospital, is the mantra of the oncology practice. While the three standard treatments for cancer in humanssurgery, radiation therapy, and chemotherapyhave been adapted successfully to help animals with cancer, the goal of treating cancer in the veterinary patient is to prolong good quality of life for as long as possible, not to cure the disease. Dr. Lili Duda, radiation oncologist at Ryan and editor of the veterinary section of Penns OncoLink website (http://www.oncolink.com), puts it this way: Were not willing to undertake an aggressive treatment that might cure half of our patients if it is very likely that it will make the other half suffer from serious and even fatal complications. To that end, treatment in animals is typically less aggressive than in humans, where the usual goal is curing the cancer.
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