Page 466 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

444 PART IV Specific Malignancies in the Small Animal Patient

with piroxicam. 108,110 However, nonsteroidal antiinflammatory (301 days compared with 138 days) and overall MSTs (505 days
drugs (NSAIDs) and toceranib have been shown to significantly compared with 220 days) than mandibulectomy or maxillectomy
A smaller tumor size improves the outcome after RT,
alone.
94,111
In
improved outcomes in cats with measureable oral SCC.
115
VetBooks.ir one study of 23 cats with oral SCC with no previous treatments, with a median PFS time of 45 months for dogs with T1 tumors
toceranib and/or an NSAID resulted in a biologic response rate
compared with 31 months and 7 months for T2 and T3 tumors,
of 57%, with a complete response in 4% of cats, partial response respectively.
43
in 9% of cats, and stable disease in 43% of cats. 111 The MST
of cats treated with toceranib and/or an NSAID (123 days) was Osteosarcoma
significantly longer than the 45-day MST for cats not treated
with toceranib. 111 Cats with a biologic response to treatment with OSA of axial sites is less common than appendicular OSA and
toceranib and/or an NSAID had significantly better median PFS represents approximately 25% of all cases. Of the axial OSA,
10
(112 days) and overall MSTs (202 days) than cats that did not the mandible and maxilla are involved in 27% and 16% to 22%
respond to treatment (29 days and 73 days, respectively). 111 Cats of cases, respectively. 10,118 The prognosis for dogs with oral OSA
treated with an NSAID also had a significantly improved MST is better than for those with appendicular OSA because of an
(169 days) than cats not treated with an NSAID (55 days). 111 As apparent lower metastatic potential. 10,119–122 In one study, only
most of these small case series are retrospective in nature, caveats 4% of 183 dogs with maxillary, mandibular or calvarial OSA
12
as to the true efficacy of these therapeutic approaches await con- had evidence of metastasis at the time of diagnosis, with dis-
formation in controlled, randomized trial settings. tant metastasis reported in 32% to 46% of dogs after definitive
Pamidronate, a bisphosphonate drug with antiosteoclastic treatment. 12,24
activity, has been shown to reduce proliferation of feline cancer The outcome after mandibulectomy alone is variable, with
cells in vitro and palliate cats with bone-invasive tumors, includ- MSTs of 14 to 18 months and 1-year survival rates of 35% to
ing oral SCC. 112 In a pilot study of five cats with oral SCC treated 71%. 10,20,119 After mandibulectomy, local recurrence and metas-
with pamidronate, some of which were treated with other modali- tasis has been reported in 15% to 28% and 35% to 58% of dogs,
ties including NSAIDs, the median PFS time and overall MST respectively. 20,121,122 The median metastasis-free interval and
were 71 days and 170 days, respectively. 112 MST were 627 days and 525 days, respectively, in one study of
50 dogs. 122 After maxillectomy, local recurrence and metastasis
Fibrosarcoma were reported in 58% and 32% of 69 dogs, respectively. 121 The
MST for dogs with maxillary OSA varies from 5 to 10 months,
The prognosis for dogs with oral FSA is guarded. These are locally with a 1-year survival rate of 17% to 27% and with local tumor
aggressive tumors and local control is more problematic than recurrence rather than distant metastasis being the most common
metastasis. Metastasis is reported to the regional LNs in 19% to cause of death. 10,21,118,121
22% of dogs and to the lungs in up to 27% of dogs. 12,20–24,43,113– Local tumor control is the most challenging problem and
117,179 Multimodality treatment of local disease appears to afford resecting oral OSAs with complete surgical margins is imperative.
the best survival rates, with combinations of surgery and RT or The completeness of excision was prognostic for both local tumor
RT and hyperthermia. 115 recurrence and survival in multivariate analyses in one study. 121
Surgery is the most common treatment for oral FSA. Local The combination of surgery with either RT or chemotherapy has
recurrence has been reported in up to 54% of dogs overall, 24,179 not resulted in improved outcomes in dogs with incompletely
20
up to 59% of dogs after mandibulectomy, and up to 40% of resected tumors, highlighting the necessity for an aggressive surgi-
21
dogs after maxillectomy. However, a recent retrospective series cal approach. 120,121 These results are supported by another study
reported local recurrence in 24% of 29 dogs with mandibular of 45 dogs with axial OSA in which favorable prognostic factors
and maxillary FSA. 114 Local tumor recurrence was significantly included complete surgical excision, mandibular location, and
associated with incomplete excision and breed (golden retriever or smaller body weight dogs. 118 Other poor prognostic factors for
golden retriever mixed breed dogs). 114 Two of the seven dogs with dogs with mandibular, maxillary, and/or calvarial OSA include
local tumor recurrence developed recurrence after incomplete serum alkaline phosphatase levels greater than 140 units/L,
excision and adjunctive RT. 114 In older reports, the 1-year survival increased monocyte counts, telangiectatic histologic subtype,
rates rarely exceed 50% with surgery alone; 13–23 however, the MST mitotic index, histologic grade, and local tumor recurrence. 121,122
in a recent retrospective series was 743 days with a median PFI of The role of chemotherapy in the management of dogs with oral
greater than 653 days and 1- and 2-year survival rates of 88% and OSA was considered controversial because local tumor recurrence
58%, respectively. 114 The median DFI for five cats treated with was the most common cause of tumor-related deaths; however,
90
mandibulectomy was 859 days. The combination of surgery and adjuvant chemotherapy results in significantly longer metastasis-
RT may provide the best opportunity to control local disease in free intervals and STs in dogs with mandibular OSA. 122
dogs regardless of completeness of excision. 115
Oral FSAs are considered radiation resistant in the macroscopic Peripheral Odontogenic Fibroma
(gross) disease setting. 116 The mean ST of 17 dogs treated with RT
alone was only 7 months. 116 When RT is used as an adjunct to The prognosis for dogs with peripheral odontogenic fibromas
surgical resection, local tumor recurrence was reported in 32% is excellent after treatment with either surgery or RT. These are
of dogs overall and the MST increased to 18 to 26 months with benign tumors, and metastasis has not been reported; hence, local
a 1-year PFS rate of 76%. 43,117 In one study, 17 of 48 dogs with tumor control is the principal goal of therapy. The local tumor
oral FSA were treated with adjuvant hypofractionated RT and RT recurrence rate after surgical resection without bone removal var-
did not provide a protective effect with significantly poorer STs ies from 0% to 17%, 125,126 whereas a 4% local recurrence rate
in dogs treated with RT. 179 However, in another study, the addi- was reported in one study of dogs treated with either mandibulec-
tion of RT to surgery resulted in significantly longer median PFS tomy or maxillectomy. RT is also effective, with an 3-year PFS
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