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Pet Docs: Vaccines for dogs with bone cancers may do some good, need improvement

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Perry Jameson (left) and Henri Bianucci. File/Staff

Q: My dog, Buck, has recently been diagnosed with cancer in his bone. This was based upon an X-ray that was taken when he started limping. The vet said he could biopsy the tumor to be sure, but that based upon the appearance of it, he was virtually certain of the diagnosis.

He said that it is osteosarcoma, and that the leg will need to be amputated to relieve pain. He said that the cancer will likely spread and ultimately he will die of this in about 8 months.

I have read that some of the tumor can be sent off to a laboratory and processed into a vaccine against the cancer. Would you consider this treatment?

A: There are a few small studies looking at this modality, with mixed results. The process here is to remove a tumor in whole or in part, and submit the tissue to a specialized lab. They will process the material into a vaccine, and return it to your veterinarian's office, where it will be administered to the patient in a series of injections.

The theory is that the body will react to this tissue and form antibodies against the tumor cells. The trick is to find, or expose, some element of these cells that the body will see as foreign, and then mount an immune response against the cancer cells.

A recent study indicated that such a vaccine did demonstrate a statistically significant effect against a cancer known as hemangiosarcoma, versus patients who had surgery alone. However, the survival times were not much better than what is seen with conventional chemotherapy, the study size was not large and there are nutritional supplements that have demonstrated similar effects against that cancer.

If I’m (Henri Bianucci) starting to sound skeptical, it does not mean I am against this approach in general, I just think we need more data before we can hang our hats on it. These vaccines are being deployed against cancers that are seldom cured by surgery alone, and may be only marginally responsive to conventional chemotherapy and radiation. So, what do we have to lose by trying them?

Financially, the vaccine is moderately priced when compared to chemotherapy or radiation. Safety studies have not shown any significant negative side effects that would preclude the use of these vaccines.

Localized injection site pain, swelling, fever are all pretty standard vaccine reactions. The real question is efficacy, or how predictably they yield benefit. In my opinion, the studies suggest that there may be some benefit in some patients. Do I believe they are a cure? At present, no.

As I said, I do believe that they are on the right track, and that ultimately, the closest we will get to cancer cures will come from our ability to harness the awesome power of our own immune systems.

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Max was a Rottweiler that I saw about 15 years ago because of a severe lameness, which turned out to be because of osteosarcoma affecting his leg. He was an older dog, was overweight and had multiple orthopedic issues affecting virtually all of his joints. To say the least, he was not a good candidate for amputation. When we saw the X-rays, it was pretty clear what was wrong, but because amputating his leg would be so hard on him, we decided to biopsy the bone tumor first.

A bone biopsy involves using a trephine. Think of those big tubes that we drill into the earth to obtain core samples. As you can imagine, these are disruptive to tissue, and the body will react to this trauma with an inflammatory response. This also can trigger an immune response.

In Max’s case, the biopsy confirmed our suspicions, but since he was continuing to use the leg, and there is no real advantage to early amputation, we decided to wait and buy a little time.

The problem was that not only did he not get worse, he started doing better. Weeks rolled past and we decided to get another X-ray, and we were stunned by the results. The tumor lesion had completely resolved.

I did a little research, and found that there were a few cases in which an osteosarcoma lesion was biopsied, and this was followed by spontaneous resolution of an otherwise deadly cancer. Since Max’s case, I have had two additional cases of osteosarcoma, and one of an equally serious intestinal cancer, that resolved following biopsy harvesting. So, what happened?

My best guess is that in the course of obtaining the biopsy, there is a disruption of the cells, and the body reacts to this invasion.

I assume that some protein unique to the tumor cells was exposed and recognized as foreign by the immune system, which reacted and eliminated the cancer. In one of the osteosarcoma cases, the cancer returned a year later at the same site as the original mass. This is still well beyond the average survival time with surgery alone.

The common thread in each of my cases was that a biopsy was performed, and was not followed closely by amputation. These cases all had delayed procedures, which allowed the body time to react. I wonder what would happen if more cases were allowed similar delays, giving their immune systems time to react.

Does something similar happen with these tumor vaccines? Presumably so.

But there are probably individual patient variations that make each one more or less likely to respond positively to the vaccinations.

As our understanding of these variables improves, I’m sure the efficacy of these types of vaccines also will improve. For now, would I try it on my dog? Given that it passes the "do no harm" rule, and it may do some good, and believing as I do that the cure will ultimately come from within us, yes, I would consider it.

Dr. Henri Bianucci and Dr. Perry Jameson are with Veterinary Specialty Care LLC. Send questions to petdocs@postandcourier.com.

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