Page 468 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

446 PART IV Specific Malignancies in the Small Animal Patient

Surgical resection is recommended, 141 whereas RT is reserved of 4 and 3 months reported for grade II and III SCC, respec-
for MMs, inoperable cancer, or tumors metastatic to the regional tively. 139 The 1-year survival rate is 50% after complete surgical
resection and approaches 80% with complete histologic excision
LNs. Surgical resection, involving either marginal excision, sub-
VetBooks.ir total glossectomy, or total glossectomy, was well tolerated in one of low-grade SCCs. 139 Long-term control of feline tongue tumors
is rarely reported with 1-year survival rates for tongue SCC less
study of 97 dogs.
Complications included postoperative bleed-
141
ing (10%), partial tongue paralysis (2%), and incisional dehis- than 25%.
cence (2%); and no dog had long-term prehension difficulties. 141 The MST for dogs with tongue MM is variable, with 222 days
Resection of 50% to 100% of the tongue or avulsion of the tongue reported in one study, 140 but not reached and was greater than
9
was reported in five dogs with minimal postoperative problems, 551 days in another study. The metastatic rate ranges from 29%
which suggests that more aggressive resections may be possible to 45%. 9,138,140,141
without compromising quality of life. 189 Feeding tubes are rec- The overall MST for 20 dogs with surgically treated lingual
ommended for enteral nutrition during postoperative recovery hemangiosarcoma was 553 days. 142 Lingual hemangiosarcomas
after total glossectomy but, in the long term, eating and drinking are typically small, located on the ventral aspect of the tongue,
are usually only mildly impaired and good hydration and nutri- and low to intermediate histologic grade. 142 Prognostic factors
tion can be maintained postoperatively. 139,189 Hypersalivation is included tumors causing clinical signs and larger tumors. Dogs
the most common complaint after aggressive resections. 189 Ther- with clinical signs associated with their lingual hemangiosarcoma
moregulation can be a problem in hot and humid environments. had a significantly shorter MST (159 days) than asymptomatic
Grooming in cats will be compromised and may result in poor dogs (633 days). 142 The MST for dogs with lingual hemangiosar-
hair-coat hygiene. comas less than 2 cm (633 days) was significantly longer than for
The prognosis for tongue tumors depends on the site, size, dogs with tumors 2 cm to 4 cm (150 days). 142
type, and grade of cancer, completeness of excision, local tumor Granular cell myoblastoma is a curable cancer. 192 These cancers
recurrence, and metastasis. 139–141 Cancer in the rostral tongue has may look large and invasive, but are almost always removable by
a better prognosis, possibly because rostral lesions are detected conservative and close margins (Fig. 23.9). Permanent local con-
at an earlier stage, the caudal tongue may have richer lymphatic trol rates exceed 80%. 192 They may recur late, but serial surgeries
and vascular channels to allow metastasis, and rostral tumors are are usually possible. Metastasis is rare with this cancer.
easier to resect with wide margins. 139 Tumor size was prognostic
in two studies. In one study, dogs with tongue tumors greater than
4 cm were 10 times more likely to develop local recurrence and/
2
or distant metastasis and up to 19 times more likely to die of their
2
tongue tumor than dogs with tumors ranging from 1 cm to 4
2 140
cm . In another study, tumor size was the only variable prog-
nostic on multivariate analysis; dogs with tumors less than 2 cm
had a MST of 818 days compared with 207 days for dogs with
tumors 2 cm or greater. 141
Complete surgical excision was significantly more likely with
smaller tumors and tumors located in the rostral free portion of
the tongue. 139,140 Furthermore, complete surgical excision was sig-
nificantly associated with increased STs and dogs with incomplete
histologic margins were significantly more likely to develop local
recurrence and/or distant metastasis and die of their tumor. 139,140
Local tumor recurrence has been reported in 26% to 28% of dogs
after glossectomy, and is more likely with incomplete histologic
excision, large tumors, and malignant tumors. 140,141 Dogs with
local tumor recurrence were 33 times more likely to die as a result
of their tumor than dogs without local recurrence. 140
Dogs with benign tongue tumors have a significantly longer
DFI and MST than dogs with malignant tongue tumors. 140 In
one study, the MST for dogs with benign tongue tumors was not
reached and greater than 1607 days compared with 286 days for
dogs with malignant tongue tumors. 140 Dogs with malignant
tongue tumors were eight times more likely to have local recur-
rence and/or distant metastasis and 15 times more likely to die
of their tumor than dogs with benign tongue tumors. 140 Dogs
with metastatic disease have a significantly worse outcome, with
an MST of 241 days compared with a MST of 661 days for dogs
without metastatic disease. 141
Tongue SCCs in dogs are graded from I (least malignant) to
III (most malignant) based on histologic features such as degree
of differentiation and keratinization, mitotic rate, tissue and vas-
cular invasion, nuclear pleomorphism, and scirrhous reaction. 139 • Fig. 23.9 This large granular cell myoblastoma was easily removed
The MST for dogs with grade I tongue SCC is 16 months after surgically. The dog had a recurrence 2 years postoperatively, which was
surgical resection, which is significantly better than the MSTs resected again, and the dog is tumor free 3 years after the second surgery.