Page 1320 - Clinical Small Animal Internal Medicine

1258 Section 11 Oncologic Disease

Computerized treatment planning using CT images of the patients experienced significant late side‐effects
VetBooks.ir patient are recommended to enhance normal tissue spar- including rhinitis (bacterial and fungal), osteomyelitis,
and fistula formation. A study in 2011 evaluated defini-
ing while ensuring appropriate dose distributions within
the tumor. For IMRT, CT and computer planning is
found that reirradiation is a viable treatment option for
required. Stereotactic radiation, which is similar to IMRT, tive reirradiation of nine dogs with nasal tumors and
is the specific treatment of choice for most nasal tumors. canine nasal tumors with tolerable acute and late side‐
Protocols consist of the precision delivery of curative intent effects. The MST time for the patients in this study was
therapy in 1-3 high dose fractions. 30 months.
With stereotactic and/or traditionally fractionated
IMRT, acute toxicities that effect the rapidly dividing tissue Feline Nasal Tumors
of the oral cavity, nasal cavity, skin, and eye can be seen, but Reports of treatment for feline nasal tumors are
are typically very limited. Oral antibiotics, analgesics, and/ lacking. One study including 16 cats with nonlym-
or artificial tears can be used as needed to counteract and phoproliferative neoplasms treated with a definitive
support any treatment related side effect. Life limiting late course of radiation to a total dose of 48 Gy reported
side effects such as bone or brain necrosis are possible, but a MST of 12 months. This treatment resulted in
the risk is expected to be less than 5%. minimal acute side‐effects and modest chronic ocular
Palliative radiation therapy can also be considered for the side‐effects. When radiation therapy protocols are
treatment of nasal tumors. With palliative radiation proto- used for the treatment of feline nasal lymphoma,
cols, side‐effects are limited. Alleviation of clinical signs has long‐term control of local disease is favorable and it
been reported in up to 95% of dogs treated, with median has been reported that higher total doses (greater or
survival times reported to be approximately 4–6 months. equal to 32 Gy) of radiation therapy may confer an
Chemotherapy has also been evaluated for the treatment of additional survival benefit. The role of chemotherapy
nasal tumors in dogs. Clinical responses are seen with for the treatment of feline nasal lymphoma is unde-
chemotherapy, but the response is usually not durable. fined. Median survival times for cats receiving radia-
tion therapy +/‐ chemotherapy for the treatment of
nasal lymphoma range from 13 to 31 months.
Prognosis
Canine Nasal Tumors
The long‐term prognosis for dogs with nasal tumors is Cancer of the Pharynx
very dependent on the treatment pursued. A retro-
spective study of 139 dogs with nasal tumor evaluated Pharyngeal tumors are rare and little information has
those that did not receive therapy. Their overall median been reported in literature. In cats, lymphosarcoma
survival time was approximately three months. This is the most commonly reported. In dogs, extramed-
study also found that dogs presenting with epistaxis ullary plasma cell tumor, osteosarcoma, chondrosar-
had a significantly shorter median survival time than coma, fibrosarcoma, and carcinomas have all been
those without epistaxis. Surgery as the sole treatment reported. Malignant tumors of the pharynx are more
of nasal tumors results in a median survival time of common; however, benign tumors have been reported
only 3–6 months, with a high rate of acute and chronic in dogs. These include rhabdomyoma, angioleiomy-
morbidity. Curative‐intent, high‐energy megavoltage oma, and oncocytoma. Rhabdomyomas are mini-
radiation alone results in a median survival time of mally invasive and have a predilection for young
8–19.7 months, with one‐ and two‐year survival rates male dogs.
ranging from 43% to 60% and 11% to 44%, respectively. Surgery is the treatment of choice for pharyngeal
The combination of surgery followed by postoperative tumors. Many benign tumors can be removed while
radiation reports survival times ranging from 4.1 preserving function, while radical procedures such as
months to 15.2 months, adding no benefit to radiation permanent tracheostomy and complete laryngectomy
therapy alone. In a small series of 13 dogs that under- are required for malignant tumors. Chemotherapy
went preoperative radiation followed by surgical exen- and radiation therapy can also be considered. Surgical
teration of residual disease, a survival advantage was removal of pharyngeal rhabdomyoma is often consid-
demonstrated (MST 47 months). However, these ered curative.