The Dog Cancer Survival Guide (111 page)

It can be difficult to come up with a prognosis for nasal tumors, because while there are actually three separate staging systems, each of which measures the extent of the tumor and how much bone invasion is present, none actually helps us predict either the course of the disease or the prognosis. I don’t find them helpful, so I have left them out of this book.

There is some evidence that tumors extending into the sinuses, eyes and their surrounding tissues, and/or the bone that separates the nose from the brain, are more serious than other nasal tumors. The factors have not been confirmed with enough studies, so at this point, one nasal tumor cannot yet be definitively labeled as “worse” than any other.

In general, if nasal tumors are left untreated, afflicted dogs have a median survival time of three months.

For most cancers, we use surgery to remove the tumor, then follow up with radiation to kill microscopic local spread and/or chemotherapy to treat distant metastasis. Nasal cancer is different: by the time of diagnosis most tumors have invaded the bone, making clean margins nearly impossible. Removing bones in the skull can have a marked disfiguring effect on your dog, and surgeries are rarely effective as a standalone treatment (resulting in median survival times of only three to nine months).

Unless the tumor is a rare case –
very
small and well-defined – surgery is not the first course of treatment. It’s not even used to debulk (reduce the size of) tumors before other treatments. These surgeries tend to increase side effects and don’t do anything to prolong life. Instead, to control the tumor, reduce pain and extend life, the standard of care is radiation therapy.

There are many published protocols for radiation therapy and most require multiple treatments. Using radiation therapy for sarcomas, especially chondrosarcomas, results in the best prognosis: median survival times of thirty months. Dogs with adenocarcinoma (ACA) live about twelve to eighteen months with radiation therapy. Undifferentiated sarcomas and SCC (squamous cell carcinoma) fare worse, with survival times from eight to ten months with radiation therapy.

The conventional treatments Dr. Ettinger recommends for nasal tumors should be considered part of step one of Full Spectrum cancer care (
Chapter 11
). Please review that chapter for more general information about surgery, radiation and chemotherapy and how to handle their common side effects.

For more information on all other Full Spectrum steps, including nutraceuticals, immune boosters, dietary changes and brain chemistry modification strategies, review Full Spectrum cancer care, which begins on
page 103
.

You will also find information about specific chemotherapy agents in
Chapter 41
.

It is important to remember that radiation does not destroy cancer cells instantly: it damages their DNA and they die later, when they try to divide. As a result, radiation therapy does not show instant results – the tumor remains largely the same size immediately after treatment. The most reduction will be seen three to six months after treatments end. In the meantime, oral antibiotics, pain medications and eye medications may be needed, to manage side effects.

Radiation does carry undeniable and unavoidable side effects. Typically, during the second half of therapy and in the first few weeks after radiation, there is inflammation in the field of treatment. Because of the location of nasal tumors, this usually means inflammation of the nasal and oral mucous membranes, the skin and the eyes. This will go away over time, usually within a few weeks. Side effects that occur later (months to years later) are often permanent. Many dogs develop a condition called dry eye, in which the tear ducts are damaged and stop lubricating the eye. This condition requires daily, lifelong administration of eye medications. Another side effect is eye cataracts, which can be surgically corrected. You will have to weigh the benefits of life extension, tumor control and pain management against the risks of these side effects. My opinion is that most dogs tolerate this treatment, live longer and have a good quality of life.

Although surgery
prior
to radiation therapy is not generally helpful, using surgery
after
radiation, to remove residual or recurrent tumors, may significantly extend survival time. In a recent study, the median survival time with surgery increased to forty-eight months, compared to radiation therapy alone: twenty months in the study. Side effects did increase: nasal inflammation, bone inflammation and dead bone (osteonecrosis). This study was relatively small and is not yet the standard of care; it may be helpful for your dog.

If stereotactic radiosurgery, 3-D conformal radiation or intensity-modulated radiation (IMRT) is available to you, you might consider these exciting new forms of radiation therapy. These tools deliver higher doses more accurately, with less exposure of normal tissue than traditional radiation, which radically reduces side effects.

Fewer treatments are typically needed with stereotactic radiosurgery, as well. My radiation colleague and I have treated over fifty nasal tumors with our CyberKnife radiosurgery machine, so far. Although it is still too early to fully evaluate the outcome of these surgeries, average survival times are well over a year and significant side effects, like skin burns and mucositis, are dramatically reduced.

There are some drugs that act as radioprotectors (protecting normal tissue from radiation exposure) and radiosensitizers (enhancing tumor cell kill). Not yet fully explored for canine nasal radiation therapy, they have been helpful in people. For example, the radioprotector amifostine decreases early and late side effects in humans and allows treatments to be given without breaks. If using drugs like these in dogs can extend survival time or decrease toxicity, they may be worth future studies and your consideration.

Some chemotherapy drugs are known to increase the sensitivity of tumors to radiation in humans; the best protocols have not yet been worked out for dogs. We are also not sure if using chemotherapy drugs actually improves sensitivity in dogs or extends survival times.

Some dog owners want to know whether using chemotherapy as a standalone treatment is worthwhile. Unfortunately, it doesn’t seem to be helpful for extending life. Platinum-based protocols (carboplatin and cisplatin) may be considered for symptom relief; they do not extend life.

Palliative radiation therapy is an option to consider if a full course of radiation does not appeal to you. Usually given in one to four treatments (rather than the fifteen to twenty used in conventional radiation), it is less expensive than conventional radiation or stereotactic radiosurgery and associated with fewer early side effects, too. However, the response does not last as long; in one study, 95% of dogs had symptom improvement, 40% had treatment-induced side effects and the median survival time was seven months.

Oral piroxicam or other NSAIDs may help nasal tumors, especially carcinomas, because of their anti-inflammatory and anti-cancer properties. Keep in mind that dogs should be on only one NSAID at a time, and they should not be combined with steroids. The use of more than one anti-inflammatory agent can increase the risk of stomach ulceration.

Nasal tumors are tough cancers to treat with any therapy other than radiation, and they are not likely to be cured. Even so, I consider them treatable cancers; radiation can extend life, control symptoms and make dogs much more comfortable than they are at diagnosis.

S
oft tissue sarcomas develop in a variety of connective tissues, muscles and fat. They can be found in sites all over the body, from head to trunk to paws, and can vary widely in their appearance and effect on the body. The majority of these tumors are usually aggressive locally, which means they invade the neighboring tissues. They are also prone to recur, although they typically don’t metastasize.

Of all the malignant tumors, having soft tissue sarcomas is not the worst-case scenario for your dog. Low and intermediate grades of soft tissue sarcomas are very treatable and have excellent long-term survival rates (some up to five years). The recommended treatments include surgery and/or radiation for low and intermediate grades, and, occasionally, chemotherapy. Chemotherapy may also be recommended for higher grades, which tend to be more metastatic and have lower survival rates (up to eight months, once lung metastasis is confirmed).

Soft tissue sarcoma is often referred to by its initials, STS. Other names for STS are mesenchymal tumor, soft part tumor and soft part sarcoma.

Soft tissue sarcomas comprise a broad group of tumors that develop in many different locations and have similar behavior, cellular features, treatment recommendations and prognoses. They can occur in any site in the body and are named for the tissue with which they are associated. STS include: hemangio-pericytomas, fibrosarcomas, peripheral nerve sheath tumors or neurofibrosarcomas, malignant fibrous histiocytomas, liposarcomas, myxosarcomas and undifferentiated sarcomas (sarcomas that cannot be specifically identified in a biopsy).