Nasal Cavity Cancer
- Common symptoms include nasal discharge, nose bleeds, “snorting”, or facial deformity.
- Radiation therapy is the current standard of care for nasal tumors.
- Median survival time after a full course of radiation treatment ranges from 8 to 19.7 months.
- Median survival time with surgery alone ranges from 3 to 6 months.
Nasal Cavity Tumors
The nasal cavity is a large air-filled space above and behind the nose. Paranasal sinuses are air-filled spaces that communicate with the nasal cavity. The most common type of cancers affecting this region are carcinomas and sarcomas, both of which are locally destructive. Carcinomas form in the lining of the nose and include adenocarcinomas, squamous cell carcinoma, and undifferentiated carcinoma subtypes. Sarcomas form in the cartilage, bone, or connective tissue within the nose. Although less frequent, other tumor types have been reported in the nasal cavity including melanoma or mast cell tumors. The metastatic rate (spread to other organs) is considered low at the time of diagnosis but can be as high as 50% at the time of death. The most common organs to which the tumors spread are the lymph nodes and the lungs, but can also include other sites like bone, kidneys, liver, skin, or the brain.
Symptoms of nasal cavity tumors in dogs
The average duration of symptoms before diagnosis is 3 months and includes bleeding from the nose, nasal discharge, facial deformity from bone erosion and tumor growth, sneezing, difficulty breathing, or eye discharge due to tumor obstruction of the ducts. Nasal bleeding or discharge will often occur in one nostril but may affect both sides over time. Some of these symptoms overlap with other medical conditions such as fungal infection, foreign body, or inflammation but as the tumor grows, signs such as facial deformity, swelling, or eye protrusion may be observed. In cases where the nasal tumor is close to the brain, the dog may suffer from seizures or behavior changes.
Diagnosis of nasal cavity tumors
To confirm a diagnosis of nasal tumors, the veterinarian will typically perform a physical exam, imaging and biopsy. Advanced imaging techniques such as CT scan and MRI are superior tools for evaluating the extent of tumors in the nasal cavity as well as for planning radiation therapy treatment. In order to definitively confirm the presence of a nasal tumor, a tissue biopsy should be obtained. This can usually be completed with a small fiberoptic instrument in a procedure called a rhinoscopy. Once diagnosis is confirmed as cancer, it is usually recommended to stage the disease (determining how extensive it is) so that an appropriate treatment plan can be developed by the veterinary oncologist. Staging of nasal tumors usually includes lymph node aspiration (to determine whether the tumor spread to the nearby lymph nodes), chest radiographs (to determine whether the tumor spread to the lungs), and blood tests/urinalysis (to determine the overall health of the pet and if the pet is well enough to undergo treatment).
Does cancer cause pain in dogs?
Pain is common in pets with cancer, with some tumors causing more pain than others. In addition to pain caused by the actual tumors, pets will also experience pain associated with cancer treatments such as surgery, radiation therapy, or chemotherapy. Untreated pain decreases the pet’s quality of life and prolongs recovery from the illness, treatment, or injury. It is, therefore, essential that veterinary teams taking care of pets with cancer should also play a vital role in educating pet owners about recognizing and managing pain in their pets. The best way to manage cancer pain in pets is to prevent it, a term referred to as preemptive pain management. This strategy anticipates pain ahead of time and administers pain medication before the pet actually experiences pain, thus ensuring the pet’s maximum comfort.
Treatment options for nasal cavity tumors
Because nasal cancer begins to invade the bone early, surgery (called rhinotomy) alone is not sufficient to control cancer and is not usually recommended. Radiation therapy directly to the affected area is currently the treatment of choice for nasal tumors and has been shown to improve survival times. The advantage of radiation therapy is that it treats the entire nasal cavity together with the affected bone and has shown the greatest improvement in survival. At this time, it is uncertain whether surgical removal of the tumor prior to radiation therapy provides even better benefit to the patient. The radiation therapy is typically delivered in 10 to 18 treatment sessions over the course of 2 to 4 weeks, thus requiring commitment from the pet owners to complete the course of radiation treatment. More recent protocols involving one treatment per week for 3 weeks have demonstrated efficacy as well. It has been shown that megavoltage radiation therapy results in better survival compared to cobalt radiation therapy. The use of CT imaging prior to initiating radiation therapy can be of tremendous help for effectively directing radiation only toward the affected area while sparing normal healthy tissue. It should be emphasized that radiation therapy is remarkably well-tolerated in animals and usually can reduce or resolve disease symptoms in a short period of time.
For pets unable to undergo radiation therapy, chemotherapy is an option, but one with limited efficacy that does not improve overall survival times. If the tumor is small and did not invade surrounding tissues, surgical removal may be an option; however, very few dogs meet these criteria at the time of diagnosis. As mentioned above, surgical removal of large and/or invasive tumors does not provide any substantial benefit.
What are the side effects of radiation therapy?
Unfortunately, radiation therapy will affect some normal tissues that cannot be excluded from the radiation field (the area scheduled for irradiation). The amount of damage will depend on the daily dose of radiation, total radiation, and how much of the tissue is being treated. Immediate side effects of radiation therapy usually include inflammation of the oral cavity (mouth), inflammation of the nasal cavity, shedding of the skin, and eye dryness. It is very important to prevent any additional damage to the area caused by the pet’s pawing or licking so Elizabethan collars should be used as needed. The majority of animals tolerate this therapy surprisingly well.
Prognosis for dogs with nasal cavity tumors
One study of 139 dogs showed that without treatment, the average survival time is 95 days. Another study showed that dogs that underwent surgery alone had a median survival of 3 to 6 months, which is comparable to that reported for no treatment. Prognosis of dogs who show symptoms of nasal bleeding appears to be worse (medial survival of 88 days) compared to those without it (medial survival of 224 days). The median survival time after a full course of radiation treatment alone ranges from 8 to 19.7 months and 43 to 60% of dogs are alive 1 year after radiation and 11 to 44% are alive 2 years after radiation. The use of CT imaging to plan radiation treatment can increase the survival range to 11 to 19.7 months. Although radiation therapy alone is able to provide local control of nasal tumors for approximately 10 months, and thus prolong the patients’ overall survival, most dogs will eventually die or are humanely euthanized as a result of local disease progression.
Several characteristics are associated with poorer outcomes (shorter survival) in dogs with nasal tumors such as the patient being over 10 years old, having a tumor-induced facial deformity, presence of lymph node or other organ metastasis, or lack of resolution of clinical signs after radiation therapy.