Page 524 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

502 PART IV Specific Malignancies in the Small Animal Patient

including one complete tumor response and improvement of plate involvement as determined by CT imaging (stage 4) have
clinical signs in five dogs. 164 The median duration of treatment the shortest disease-free survival (DFS) and overall survival time
(OST). This subset of dogs had a median DFS of 3.8 months and
was 18 weeks. Use of toceranib in combination with RT has not
VetBooks.ir yet been reported. In three dogs with SCC limited to the frontal a median OST of almost 7 months, compared with dogs with uni-
lateral tumors without bone involvement (stage 1) in which DFS
sinus, tumor responses including two complete responses were
observed with piroxicam and carboplatin. The third dog had a and OST were 6.5 and 23 months, respectively. In a recent study of
marked tumor response when toceranib was substituted for 29 dogs with cribriform involvement (stage 4) treated with defin-
carboplatin. 165 itive-intent IMRT, the MST was 305 days. 177 Compared with the
Electrochemotherapy has been described in dogs with nasal earlier studies that used nonconformal delivery techniques, 105–106
cavity tumors, consisting of an intravenous injection of bleomy- these favorable results suggest that IMRT, with its greater confor-
cin followed by local delivery of electric pulses using a custom mality and tumor dose homogeneity, may improve outcomes in
single needle electrode to potentiate drug uptake. 166 The overall dogs with stage 4 disease. Interestingly, intracranial tumor exten-
response rate in 11 dogs treated with electrochemotherapy alone sion past the cribriform plate was not prognostic for survival. 177
was 90% with a MST of 16.9 months, compared with 5.3 months This highlights the fact that prognostic indicators may change as
in 10 dogs treated with surgery followed by adjuvant carboplatin technical advances in treatment develop. In most studies, sino-
chemotherapy. Systemic effects were not reported. Adjuvant elec- nasal carcinomas and sarcomas are grouped together because of
trochemotherapy using a topical application of bleomycin in the a similar biological behavior and clinical response to RT. In the
nasal cavity is reported in a single dog after surgical extirpation of multiinstitutional study of 94 dogs mentioned above, 106 there was
the tumor. 167 no effect on clinical outcome when all carcinomas were compared
Other therapeutic approaches to nasal tumors that have been with all sarcomas; however, when dogs with anaplastic carcinoma,
investigated include proton-beam therapy, brachytherapy, immu- undifferentiated carcinoma, and SCC were grouped together, they
notherapy, cryotherapy, and photodynamic therapy (PDT). had a shorter DFS than dogs with other tumor types. A recent
Charged particles like protons have a well-defined tissue range retrospective study limited to dogs with sinonasal sarcoma treated
and sharp dose fall off, which could potentially be exploited for with RT (n = 86), the overall MST was 444 days (15 months),
28
conformal tumor targeting and normal tissue sparing. 168 A small which is in line with previous studies. Radiation protocols were
clinical trial involving nine dogs with nasal tumors treated with not standardized, but dogs with sarcoma treated with definitive
proton-beam therapy resulted in tumor responses and survival RT had more favorable outcomes compared with those treated
times similar to those reported for MV irradiation. 168 Acute in the palliative setting (MST 523 days vs. 305 days). Also, dogs
effects to the skin and eyes were pronounced in some dogs, and treated daily Monday to Friday had an improved MST compared
50% of dogs developed radiation-induced cataracts. Due to lim- with dogs treated on a Monday, Wednesday, Friday schedule. Six
ited availability of proton irradiators, this technology is unlikely dogs diagnosed with intracavitary nasal osteosarcoma had a signifi-
to be optimized for use in dogs. Intracavitary RT using radioactive cantly better MST at 624 days than dogs with other mesenchymal
isotopes (brachytherapy) has been evaluated after surgical removal tumors. Interestingly, this is in contrast to seven dogs with nasal
of sinonasal tumors in dogs. 169–170 Potential problems associated osteosarcoma treated with SRT that had a shorter OST than dogs
with this type of radiation include dose distribution and radiation with other carcinoma or sarcoma tumor types (MST 3 months
exposure to personnel. The question of whether brachytherapy vs. 10 months). 151 This difference may be due to chance, or varia-
improves survival over traditional external-beam RT has not been tions in tumor stage, or tumor location, or treatment approaches
answered. Immunotherapy and cryosurgery have not improved in these small groups of dogs. The true prognosis of sinonasal
survival times. 25,171 A recent case report described the use of osteosarcoma treated with RT is not clear. In a multiinstitutional
image-guided cryotherapy in the treatment of a rapidly recurrent study of 24 dogs with intranasal lymphoma treated with various
nasal carcinoma that resulted in long-term tumor control and sur- RT protocols +/− adjuvant chemotherapy, the overall MST was
vival. 172 The authors suggested that further investigation of this 375 days for intermediate/large cell and 823 days for the small cell
59
technique may be warranted for the management of focal residual group. There was no difference in MST for dogs treated with
or recurrent nasal tumors. Reports evaluating PDT have been RT and chemotherapy versus chemotherapy alone. Eighty-five
published, including in combination with surgery and RT; how- percent to 90% of dogs treated with RT improved clinically, sug-
ever, results are too preliminary to draw any conclusions. 173–175 gesting that this is a radioresponsive tumor and that RT may play
When all treatments fail to control epistaxis, unilateral or bilat- a role in its management. Angiofibroma is a histologically benign
eral carotid artery ligation can palliate symptoms in dogs for up to but locally aggressive vascular nasopharyngeal tumor character-
3 months or longer without damage to the brain. 99 ized by a proliferation of irregular appearing blood vessels that
63
The importance of prognostic factors in the treatment of are surrounded by a connective tissue stroma. None of the 13
canine sinonasal tumors remains controversial. Negative predic- dogs reviewed retrospectively had metastasis. Prolonged survival
tors of survival from various studies include age (>10 years), 108 of up to 4 years was reported in four dogs after surgical excision.
epistaxis, duration of clinical signs, 155 advanced local tumor Survival of 1 to 2 years was observed in some dogs with no treat-
74
stage, 104–106,108,109 metastatic disease, 36,108,136 histologic sub- ment. A small series of four dogs with intranasal MCT receiving
type (carcinoma, particularly SCC or undifferentiated), 104,106,98 various chemotherapy agents has been reported. Tumor response
60
tumor expression of survivin, 176 and failure to achieve resolution information was not provided. The survival times ranged from 27
of clinical signs. 155 An analysis of 94 dogs with varying subtypes to 134 days. Based on a case report of three dogs treated with RT,
of nasal carcinoma or sarcoma treated with curative-intent RT intranasal melanoma appears to be a radioresponsive tumor with
61
at three veterinary facilities was performed. 106 A correlation was two dogs experiencing a complete response after RT. Finally, in
demonstrated between clinical outcome and the original Adams a case series of five dogs with nasal polyps treated with surgery or
tumor staging scheme, 105 as well as the modified Adams tumor nasal flushing, three dogs were alive without recurrence at 16 to
64
staging method. 105 Based on these findings, dogs with cribriform 54 months. Two dogs developed recurrence, one of which had