Nearly half of lingual lesions are neoplastic, although lingual neoplasia in dogs is rare overall.1 The veterinary literature describing lingual neoplasia is primarily limited to case reports and case series, and outcome data in dogs with lingual neoplasia remain poorly described. One retrospective study2 of lingual tumors identified squamous cell carcinoma as the most common lingual neoplasia diagnosed. This differs from a more recent report1 of lingual lesions that indicates that melanomas and squamous cell carcinoma account for 23% and 17% of lingual tumors in dogs, respectively. Additionally, a study by Syrcle et al3 found that malignant melanomas accounted for 25% of the lingual neoplasia cases described. A wide variety of other tumor types has been reported, including sarcomas and round cell tumors. In 2 previous reports,1,3 64% of lingual tumors were malignant.
Many dogs with lingual tumors are subclinically affected at diagnosis, and tumors are often identified incidentally on physical examination.2,3 Despite the apparent clinical sign–free course, the morbidity and mortality rates associated with lingual neoplasia are high. Additionally, considering that many tumors affecting the tongue are malignant, patients should be assessed for metastatic disease and adjuvant treatments should be considered.
Although surgical resection of lingual neoplasia is considered the primary treatment of choice,4 major concerns associated with tongue resection include incomplete excision, tumor recurrence, drooling of saliva causing regional dermatitis, alteration in food prehension, metastatic disease, and possible need for feeding-tube placement. The veterinary literature dedicated to surgical outcome in animals that have undergone resection is limited. Furthermore, adjuvant therapies used in the treatment of lingual neoplasia, such as chemotherapy and radiation therapy, are uncommonly described. Reported survival times are variable, and separate studies2,3 have found inconsistent outcomes in the 2 most common tumors affecting the tongue (malignant melanoma and squamous cell carcinoma). Therefore, further investigation into this topic is necessary to improve the staging recommendations and outcomes for lingual tumors.
The primary purpose of the study reported here was to describe the clinical characteristics, treatments (including surgery and adjuvant treatments), and outcome in a cohort of dogs with lingual neoplasia that had undergone surgical excision. An additional purpose was to assess the effect of the recorded variables on survival time.
Materials and Methods
Criteria for selection of cases—The study was performed as a multi-institutional retrospective case series approved by the Veterinary Society of Surgical Oncology. Medical records of cases from 14 institutions from the years 1995 to 2008 were reviewed, and data were recorded in a commercially available spreadsheet program.a
Dogs were included if they had a lingual tumor confirmed by histologic examination and surgical excision of the lesion was performed. Dogs were excluded from this study if they had papillomas or eosinophilic growths.
Medical records review—The following variables were recorded from the medical record: age, sex and reproductive status, breed, body weight at the time of diagnosis, clinical signs, concurrent medical conditions (other than the lingual tumor), location (apex, body, or root, and dorsal or ventral) and size of the lingual tumor, results of diagnostic imaging, type of surgery (marginal excision, subtotal glossectomy, near-total glossectomy, or total glossectomy) and other treatments (chemotherapy and radiation therapy), histopathologic diagnosis, tumor grade, presence of regional and distant metastatic disease, postoperative complications (bleeding, dehiscence, or recurrence), feeding tube usage, surgical margins (complete vs incomplete), and final outcome.
A system for defining the type of glossectomy performed was adapted from the human literature.5 Categories of glossectomy included marginal excision (surgical procedure performed with the goal of removing gross disease only), subtotal glossectomy (removal of entire free portion of the tongue and part of genioglossus and geniohyoid muscles), near-total glossectomy (removal of at least three-fourths of the tongue), and total glossectomy (removal of the entire tongue).
Statistical analysis—Median survival times were compared, survival times were evaluated via the Kaplan-Meier product limit method, and log rank analysis was used to compare survival curves among groups. Cox multivariable survival analysis was used to determine which variables were significantly (P < 0.05) associated with survival time following diagnosis of lingual neoplasia. Survival time was defined as the period from the date of surgery until the date of death. Dogs alive at the time of analysis or lost to follow-up were censored at the date of last contact. Dogs that were dead were not censored. Variables investigated as possible risk factors included age, sex and reproductive status, body weight at the time of diagnosis, presence of concurrent medical conditions, tumor location and size (median largest diameter, ≥ 2 cm vs < 2 cm), use of neoadjuvant treatment, surgery type, occurrence of postoperative complications (bleeding, dehiscence, and recurrence), use of a feeding tube, surgical margins, histopathologic diagnosis, presence of regional and distant metastatic disease, use of postoperative chemotherapy, and use of postoperative radiation therapy. Centering (ie, subtracting the mean value of the variable from each data point) was applied to continuous variables that did not have a meaningful value for 0 (eg, weight = 0 or age = 0) so that graphic presentation of the estimates would be appropriate. Any factors identified with a value of P < 0.20 on univariate analysis were tested for significance in the multivariable model. Factors with a value of P < 0.05 in the multivariable model were retained. The proportional hazards assumption was tested via Schoenfeld residuals. All analyses were performed with statistical software.b Survivor functions controlling for significant variables were plotted. For all final comparisons, P < 0.05 was considered significant.
Results
Ninety-seven dogs met the criteria for inclusion in the study. Median age was 10.5 years (range, 3 to 15.5 years), and median body weight was 26 kg (57.2 lb; range, 4 to 54 kg [8.8 to 118.8 lb]). There were 46 males (32 castrated and 14 sexually intact) and 51 females (44 spayed and 7 sexually intact). Dog breeds included mixed (n = 33), Labrador Retriever (12), Chow Chow (6), Golden Retriever (5), Standard Poodle (4), German Shepherd Dog (3), Husky (3), Australian Cattle Dog (2), Corgi (2), Giant Schnauzer (2), Shar-Pei (2), and 1 each of American Eskimo Dog, American Staffordshire Terrier, Australian Shepherd Dog, Beagle, Belgian Malinois, Bichon Frise, Border Collie, Boston Terrier, Bouvier des Flandres, Brittany, Chihuahua, Cocker Spaniel, Dachshund, German Short-haired Pointer, Jack Russell Terrier, Lhasa Apso, Maltese, Miniature Schnauzer, Nova Scotia Duck Tolling Retriever, Rhodesian Ridgeback, Rottweiler, Scottish Terrier, and Shetland Sheepdog. Thirteen dogs had concomitant medical conditions, including hypothyroidism (n = 4), autoimmune disease (1), chronic pancreatitis (1), cranial mediastinal mass (1), degenerative myelopathy (1), lumbosacral disease (1), nasal planum squamous cell carcinoma (1), sick sinus syndrome (1), thoracolumbar myelopathy (1), and thyroid carcinoma (1).
Clinical signs were mostly related to the oral cavity and included oral bleeding (n = 12), difficulty eating (11), hypersalivation (9), halitosis (9), decreased appetite (6), coughing (2), and vomiting (1). In 28 cases, the lingual tumor was detected incidentally by the owner. In 28 additional cases, the lingual tumor was detected incidentally during evaluation by a veterinarian; of the 28 cases detected by a veterinarian, 12 were specifically detected during a dental cleaning procedure.
The rostral to caudal tumor location was described in 88 dogs. The tumor was located on the apex of the tongue only in 20 (23%) dogs, the body only in 28 (32%), the root only in 23 (26%), the apex and body in 8 (9%), and the body and root in 9 (10%). The dorsal to ventral tumor location was described in 94 dogs. The tumor involved the dorsal portion of the tongue in 52 (57%) dogs, the ventral portion of the tongue in 20 (21%), and both the dorsal and ventral portions of the tongue in 22 (23%). Tumor size was recorded in 74 dogs, and the median maximum diameter was 2 cm (range, 0.2 to 7 cm). The tumor size was ≥ 2 cm in 37 dogs and < 2 cm in 37 dogs.
Preoperative lymph node aspirates were obtained in 44 (45%) dogs. In 30 dogs, both the left and right mandibular lymph nodes were aspirated, and in 13 dogs, only 1 mandibular lymph node was aspirated. A superficial cervical lymph node was aspirated in 1 dog. Lymph node metastatic disease was noted in 3 mandibular lymph nodes; all 3 dogs had lingual malignant melanoma. The results of tonsillar evaluation during oral examination were not routinely recorded.
Preoperative thoracic radiography was performed in 75 (77%) dogs. Pulmonary parenchymal disease was noted in 5 dogs and included mild bronchointerstitial pattern (n = 2), aspiration pneumonia (1), pulmonary fibrosis (1), and metastatic disease (1) in a dog with a lingual malignant melanoma. One dog had enlargement of the right side of the heart.
Neoadjuvant treatment was pursued in 5 dogs and included chemotherapy in 4 dogs and radiation therapy in 1 dog. Neoadjuvant chemotherapy protocols included carboplatin alone in 2 dogs (1 with squamous cell carcinoma and 1 with malignant melanoma), polyethylated glycol (malignant melanoma), and combination therapy with l-asparaginase, lomustine, and prednisone (lymphoma). The dog receiving neoadjuvant radiation therapy had squamous cell carcinoma and received a total dose of 48 Gy over 16 treatments.
The surgical procedure performed was recorded in 93 dogs. In the remaining 4 dogs, the surgical procedure was not recorded; however, the records indicated that a cytoreductive surgery was performed. Of the 93 dogs, a marginal excision was performed in 35 (38%) dogs, subtotal glossectomy in 55 (59%) dogs, and near-total glossectomy in 3 (3%) dogs. No dogs underwent total glossectomy. Of the dogs with tumors ≥ 2 cm, marginal excision, subtotal glossectomy, and near-total glossectomy were performed in 11, 23, and 3 dogs, respectively. Feeding tubes were placed in 7 dogs (3 esophagostomy tubes and 4 gastrostomy tubes). Surgery time was recorded in 66 dogs, and the median surgery time was 45 minutes (range, 4 to 140 minutes). The median surgery time in dogs with tumors ≥ 2 cm was 55 minutes (range, 10 to 140 minutes), and the median surgery time for dogs with tumors < 2 cm was 22.5 minutes (range, 4 to 115 minutes).
Histopathologic diagnoses included squamous cell carcinoma (n = 31 [32%]), malignant melanoma (29 [30%]), mast cell tumor (7 [7%]), hemangiosarcoma (6 [6%]), granular cell tumor (4 [4%]), chondrosarcoma (3 [3%]), fibrosarcoma (3 [3%]), lymphoma (3 [3%]), liposarcoma (2 [2%]), myxosarcoma (2 [2%]), plasma cell tumor (2 [2%]), hemangioma (1 [1%]), myoepithelioma (1 [1%]), peripheral nerve sheath tumor (1 [1%]), rhabdomyoma (1 [1%]), and undifferentiated sarcoma (1 [1%]). Complete and incomplete surgical margins were noted in 58 of 93 (62%) and 35 of 93 (38%) dogs, respectively. Of the tumors ≥ 2 cm diameter, 23 were removed completely and 13 were described as having incomplete margins. Of the tumors < 2 cm, 26 were removed completely and 8 were described as having incomplete margins.
Seventeen (18%) dogs received traditional adjuvant chemotherapy (including corticosteroids and NSAIDs), and 9 (9%) dogs received a therapeutic melanoma vaccine. Chemotherapy protocols included carboplatin alone (n = 4 dogs), piroxicam alone (4), lomustine and prednisone (2), carboplatin and piroxicam (1), cisplatin alone (1), doxorubicin alone (1), intralesional triamcinolone (1), meloxicam alone (1), cyclophosphamide-doxycycline-piroxicam (1), and vinblastine alone (1). Adjuvant radiation therapy was administered to 5 (5%) dogs. The tumor types of the dogs receiving adjuvant radiation therapy included malignant melanoma (n = 3), liposarcoma (1), and lymphoma (1). Six doses were administered to 4 of the 5 dogs, and 4 doses were administered to 1 dog; total dose could only be identified in 1 medical record and was 36 Gy.
Complications associated with surgery were uncommon. Postoperative bleeding occurred in 10 of 97 (10%) dogs; bleeding was considered mild to moderate in those cases, and intervention was not necessary. Two dogs developed partial tongue paralysis. Dehiscence of the surgical wound occurred in 2 dogs. In both cases, surgical closure was not pursued and both wounds healed successfully. In all dogs for which long-term follow-up was available (n = 62), prehension was noted to be normal; the time from surgery to normal prehension of food was not universally recorded and was not reported here.
Eighteen (19%) dogs developed metastatic disease, with 1 dog having 2 sites of metastasis. Of those cases, metastatic disease was noted in 4 lymph nodes (in 4 dogs) at a median of 51 days after surgery (range, 28 to 162 days); 3 dogs had lymph node metastasis at the initial evaluation. Nine dogs developed pulmonary metastatic disease in a median of 205 days after surgery (range, 84 to 818 days). Three dogs developed metastatic disease at another location, including the proximal portion of the tibia (n = 1), brain (1), and lip (1). Malignant melanoma (n = 11) and squamous cell carcinoma (6) accounted for most cases of metastatic disease; the remaining case of metastatic disease was diagnosed as lingual hemangiosarcoma.
Twenty-seven (28%) dogs had local recurrence of the lingual tumor in a median of 127 days (range, 18 to 593 days). Fifteen of the 27 (56%) dogs with recurrence had undergone an incomplete resection, as determined on the basis of histologic evaluation. Tumors ≥ 2 cm accounted for 13 of 27 (48%) of the cases of recurrence. Nineteen cases of recurrence were squamous cell carcinoma (n = 10) or malignant melanoma (9). Of the dogs that developed recurrence, 16 of 27 (59%) underwent a second surgical procedure a median of 127 days (range, 18 to 593 days) after initial resection. In 10 of 16, an incomplete resection was obtained during the second surgery.
At the time of study completion, 41 dogs were confirmed to be dead, 24 were confirmed to be alive, and 32 were lost for follow-up examination. Of the 41 dogs that died, 34 were euthanized and 7 died spontaneously. The overall MST for all dogs in this study was 483 days (95% confidence interval, 274 to 824 days). The MST for dogs with squamous cell carcinoma was 216 days (range, 31 to 865 days) and for dogs with malignant melanoma was 241 days (range, 4 to 1,037 days). The results of necropsy were not universally reported or available.
Survival times were significantly (P = 0.009) different for dogs that had feeding tubes placed (MST, 207 days), compared with those that did not (MST, 532 days; Figure 1). Survival times were significantly (P = 0.028) different for dogs that developed metastatic disease (MST, 241 days), compared with those that did not (MST, 661 days; Figure 2). Survival times were also significantly (P = 0.028) different for dogs that had a tumor ≥ 2 cm (MST, 207 days), compared with those that did not (MST, 818 days; Figure 3) Three other variables had a value of P < 0.20 on univariate Cox regression analysis, including age (P = 0.06), mixed breed (P = 0.06), and histopathologic diagnosis of squamous cell carcinoma (P = 0.12). On multivariable analysis evaluating these 6 variables (n = 66, because of incomplete data for all 6 variables in some dogs), only 1 factor retained a value of P < 0.05; dogs with tumors ≥ 2 cm at diagnosis had significantly shorter (P = 0.001) survival times than dogs with tumors < 2 cm (hazard ratio, 3.92; 95% confidence interval, 1.71 to 8.93).
Kaplan-Meier survival curve for 87 dogs with lingual neoplasia that did (dashed line) or did not (solid line) have a feeding tube.
Citation: Journal of the American Veterinary Medical Association 242, 10; 10.2460/javma.242.10.1392
Kaplan-Meier survival curve for 87 dogs with lingual neoplasia that did (dashed line) or did not (solid line) have a feeding tube.
Citation: Journal of the American Veterinary Medical Association 242, 10; 10.2460/javma.242.10.1392
Kaplan-Meier survival curve for 87 dogs with lingual neoplasia that did (dashed line) or did not (solid line) have a feeding tube.
Citation: Journal of the American Veterinary Medical Association 242, 10; 10.2460/javma.242.10.1392
Kaplan-Meier survival curve for 88 dogs with lingual neoplasia that did (dashed line) or did not (solid line) have metastatic disease.
Citation: Journal of the American Veterinary Medical Association 242, 10; 10.2460/javma.242.10.1392
Kaplan-Meier survival curve for 88 dogs with lingual neoplasia that did (dashed line) or did not (solid line) have metastatic disease.
Citation: Journal of the American Veterinary Medical Association 242, 10; 10.2460/javma.242.10.1392
Kaplan-Meier survival curve for 88 dogs with lingual neoplasia that did (dashed line) or did not (solid line) have metastatic disease.
Citation: Journal of the American Veterinary Medical Association 242, 10; 10.2460/javma.242.10.1392
Kaplan-Meier survival curve for 66 dogs with lingual neoplasia that had a tumor < 2 cm in diameter (solid line) or ≥ 2 cm in diameter (dashed line).
Citation: Journal of the American Veterinary Medical Association 242, 10; 10.2460/javma.242.10.1392
Kaplan-Meier survival curve for 66 dogs with lingual neoplasia that had a tumor < 2 cm in diameter (solid line) or ≥ 2 cm in diameter (dashed line).
Citation: Journal of the American Veterinary Medical Association 242, 10; 10.2460/javma.242.10.1392
Kaplan-Meier survival curve for 66 dogs with lingual neoplasia that had a tumor < 2 cm in diameter (solid line) or ≥ 2 cm in diameter (dashed line).
Citation: Journal of the American Veterinary Medical Association 242, 10; 10.2460/javma.242.10.1392
Discussion
Tumors of the head and neck are common in dogs and often present a complex diagnostic and treatment challenge. Lingual tumors, although uncommon, represent an important subset of tumors affecting the oral cavity. The close association of the tongue to other vital structures can make surgical resection of lingual tumors challenging. Although some tumors affecting the tongue may have lower metastatic activity, the potential for aggressive local invasion in an organ important for mastication and swallowing can result in a poor outcome. Better characterization of lingual tumors and their treatments is essential.
Similar to previous reports, squamous cell carcinoma and malignant melanoma were identified as the most common tumor types of the tongue. These tumor types also represent the 2 most common tumors diagnosed in the oral cavity of dogs in general. Hemangiosarcoma was diagnosed in 4 of 99 (4%) dogs in 2 previous studies.2,3 Similarly, 6 of 97 (6%) dogs in the present study had hemangiosarcoma. The diagnosis of a lingual mast cell tumor has varied between 0% and 9% in previous studies2,3; 7% of the dogs in the present study had a mast cell tumor. Benign tumors were diagnosed infrequently (7%) in this series of cases. This differs from previous reports2,3 in which benign tumors accounted for 21% to 36% of cases. However, similar to those studies, granular cell tumor was one of the most frequently diagnosed benign tumors in the present study.2,3
In 2 previous retrospective studies,2,3 approximately 65% of cases of lingual tumors were recognized incidentally or found when an owner noted the mass when looking at the tongue. Similarly, 58% of the dogs reported in the present study had a lingual tumor detected on physical examination or when an owner saw the tongue lesion. The clinical signs noted in this cohort were mostly related to the physical presence of the mass, with oral bleeding, difficulty eating, hypersalivation, and halitosis predominating. Even though lingual tumors may often be identified in dogs with no obvious clinical signs, they have the potential to cause considerable morbidity and discomfort, and treatment should be considered in all cases.
In the dogs reported here, tumor location on the tongue was variable. The rostral to caudal distribution was approximately even from apex to root; however, tumors were more commonly located on the dorsal surface than the ventral surface. The predominantly dorsal location of lingual tumors may be explained by the fact that only dogs undergoing surgical excision of the tumor were included in the present study. Masses that are on the dorsal surface are likely to be found sooner, thus making surgical treatment feasible. Tumors on the ventral surface may grow unchecked for a longer period because these are more difficult to detect on physical examination or less likely to be noticed by the owner. Additionally, a veterinarian may more likely recommend surgery of a tumor located on the dorsal surface as opposed to the ventral surface because the expectation for obtaining a tumor-free margin is likely greater with a dorsally located tumor.
The overall metastatic rate was low (19%) in this study, and only 4 (4%) dogs were documented to have had metastatic disease prior to surgery. Three dogs had malignant melanoma in the regional lymph nodes, and 1 dog had a pulmonary metastatic lesion from lingual malignant melanoma. Although 75% of dogs in this study were evaluated before surgery via thoracic radiography, only 45% of the dogs had fine-needle aspiration of the regional lymph nodes. In 1 study6 of dogs with oral malignant melanoma, 30% of lymph nodes that were determined to have cytologic evidence of metastatic disease had normal findings on palpation. That finding suggests that all dogs with oral malignant melanoma should undergo fine-needle aspiration of regional lymph nodes despite normal findings on palpation. Therefore, it is possible that the preoperative metastatic rate was low in the present study because of a lack of regional lymph node cytologic evaluation.
Malignant melanoma of the oral cavity in dogs is highly metastatic. In 1 study,6 53% of dogs with oral malignant melanoma had metastasis to regional lymph nodes. The overall metastatic rate for lingual malignant melanoma cases specifically, appears to be slightly less than what has been reported for oral malignant melanomas, in general. In 2 studies evaluating lingual neoplasia, metastasis was noted in 2 of 72 and 5 of 113 dogs with malignant melanoma; similarly, the rate of metastasis in malignant melanoma cases in this study was 38%.
Metastasis negatively affected survival in several studies7–11 with different tumor types in dogs. A similar finding was reported here. The MST of dogs without metastatic disease was nearly 3 times longer than the MST of dogs with metastatic disease.
Tumor size is an important factor to consider when staging the disease. The size of oral malignant melanoma significantly affects prognosis.12 The median tumor size was 2 cm in the dogs of the present study. Dogs with small lingual tumors (< 2 cm) lived approximately 4 times as long as dogs with larger lingual tumors. The effect of tumor size on prognosis in dogs with lingual tumors has been reported.3 This concept holds true for many oral tumors, and when considering the oral cavity, treatment is often focused on local control of a tumor because of the life-limiting factor of recurrence. Although the use of advanced imaging diagnostic tests such as CT and MRI were not evaluated in this study, future evaluation of the use of these diagnostic tests in the preoperative evaluation of tumor size may assist surgeons in accurately predicting outcome.
Categorization of glossectomy has been described in humans and dogs.5,13 Maintaining tongue functionality and achieving local tumor control can be difficult tasks. Historically, many clinicians have avoided performing surgery in cases that would require ≥ 50% of the tongue to be removed because of concern that functionality would not be maintained. In a small case series of major glossectomies,13 5 dogs underwent surgical or traumatic amputation of a large portion (including 3 near-total or total glossectomies) of the tongue.13 In all cases, the dogs were eventually able to successfully eat.13
A marginal excision or subtotal glossectomy was performed in 97% of dogs in the present study. No cases (including dogs that underwent near-total glossectomy) were reported to have any difficulties in function, and all dogs were able to successfully eat food after surgery. Feeding tubes were rarely used (7%); however, survival times were significantly shorter in dogs that underwent placement of a feeding tube. Feeding tubes are often reserved for patients that have more substantial local disease requiring a larger surgical resection or patients that have a recent history of poor appetite or anorexia. These patients likely represent the population with most advanced disease, providing a possible explanation for the lower MST in this subset of dogs.
Recurrence of lingual tumors after excision is a major concern and negatively affects survival time.3 More than 25% of the dogs in the present study had local recurrence, and > 50% of these had undergone an incomplete resection, as determined on the basis of histologic evaluation. Of the dogs that underwent a second surgical procedure to remove a recurrent tumor, nearly two-thirds had an incomplete resection. The concern for postoperative function when most of the tongue is removed likely influenced this high rate of incomplete resection. Furthermore, some dogs of the present study may have undergone resection of the tumor with the sole goal of improving quality of life of the patient by removal of gross disease.
The use of adjuvant therapy in the treatment of lingual tumors is rarely documented. Approximately 25% of the dogs in this study received adjuvant treatment with chemotherapy or radiation therapy; additionally, 9 of the dogs with malignant melanoma received a melanoma vaccine. Adjuvant therapy did not have a survival benefit; however, the variability of tumor types, low number of dogs receiving adjuvant therapy, and lack of standardization of protocols limited the value of this finding. Further evaluation of adjuvant therapy with controlled clinical trials is necessary to determine a potential benefit in the treatment of lingual tumors. Principles of adjuvant therapy for these tumor types at other anatomic locations may help guide the decision to pursue adjuvant therapy.
Several limitations of this study should be acknowledged. Because of the retrospective nature of the study, medical record review was required, posing several difficulties, including the evaluation of incomplete records, deficient recording of variables, and missing data. Although one of the major benefits of multi-institutional collaborative research is reflected in the ability to obtain substantially more cases, this apparent advantage must be weighed against the variation that is present in the recording of data and the interpretation of results. Additionally, because lingual tumors are uncommonly diagnosed, only 97 dogs that met the inclusion criteria were identified during a 14-year period; this included 16 tumor types. It is difficult to compare outcomes and responses to therapy when such an array of tumor types is evaluated. However, the paucity of information available on lingual tumors mandates the reporting of these data.
As determined in the present study, the prognosis for dogs with small lingual tumors (MST, 818 days) and without metastatic disease (MST, 661 days) that underwent surgical excision was good. Large tumor size (≥ 2 cm) negatively affected prognosis; however, the MST in dogs with large lingual tumors still remained > 200 days. Performing a thorough oral examination on a regular basis, when possible, is highly recommended as this may allow for earlier identification of lingual tumors and allow for excision when masses are a smaller size. Additionally, the cytologic evaluation of regional lymph nodes, regardless of palpation status, is recommended. Adjuvant therapies are not routinely pursued, and recommended protocols are highly variable. Further investigation and the use of standardized protocols are recommended to determine the effect that specific adjuvant therapies may have on different types of lingual tumors.
ABBREVIATION
| MST | Median survival time |
Microsoft Excel, Microsoft Corp, Redmond, Wash.
Stata, version 10, StataCorp, College Station, Tex.
References
1. Dennis MM, Ehrhart N, Duncan CGet al., Frequency of and risk factors associated with lingual lesions in dogs: 1,196 cases (1995–2004). J Am Vet Med Assoc. 2006; 228:1533–1537.
2. Beck EB, Withrow SJ, McChesney AEet al., Canine tongue tumors: a retrospective review of 57 cases. J Am Anim Hosp Assoc. 1986; 22:525–532.
3. Syrcle JA, Bonczynski JJ, Monette Set al., Retrospective evaluation of lingual tumors in 42 dogs: 1999–2005. J Am Anim Hosp Assoc. 2008; 44:308–319.
4. Liptak JM, Withrow SJ, Oral tumors. Withrow SJ, Vail DM, Small animal clinical oncology. 4th ed. Philadelphia: WB Saunders Co, 2007; 468–469.
5. Magrin J, Kowalski LP, Sabóia Met al., Major glossectomy: end results of 106 cases. Eur J Cancer B Oral Oncol. 1996; 32:407–412.
6. Williams LE, Packer RA, Association between lymph node size and metastasis in dogs with oral malignant melanoma: 100 cases (1987–2001). J Am Vet Med Assoc. 2003; 222:1234–1236.
7. McNiel EA, Ogilvie GK, Powers BEet al., Evaluation of prognostic factors for dogs with primary lung tumors: 67 cases (1985–1992). J Am Vet Med Assoc. 1997; 211:1422–1427.
8. Ehrhart N, Dernell WS, Hoffman WEet al., Prognostic importance of alkaline phosphatase activity in serum from dogs with appendicular osteosarcoma: 75 cases (1990–1996). J Am Vet Med Assoc. 1998; 213:1002–1006.
9. Hillers KR, Dernell WS, Lafferty MHet al., Incidence and prognostic importance of lymph node metastases in dogs with appendicular osteosarcoma: 228 cases (1986–2003). J Am Vet Med Assoc. 2005; 226:1364–1367.
10. Paoloni MC, Adams WM, Dubielzig RRet al., Comparison of results of computed tomography and radiography with histopathologic findings in tracheobronchial lymph nodes in dogs with primary lung tumors: 14 cases (1999–2002). J Am Vet Med Assoc. 2006; 228:1718–1722.
11. Book AP, Fidel J, Wills Tet al., Correlation of ultrasound findings, liver and spleen cytology, and prognosis in the clinical staging of high metastatic risk canine mast cell tumors. Vet Radiol Ultrasound. 2011; 52:548–554.
12. MacEwen EG, Patnaik AK, Harvey HJet al., Canine oral melanoma: comparison of surgery versus surgery plus Corynebacterium parvum. Cancer Invest. 1986; 4:397–402.
13. Dvorak LD, Beaver DP, Ellison GWet al., Major glossectomy in dogs: a case series and proposed classification system. J Am Anim Hosp Assoc. 2004; 40:331–337.
