Prognostic factors and survival following radiation therapy for canine nasal tumors: A single-institution retrospective study of 166 cases.

Background: Prognostic factors in dogs with nasal tumors include several variables. However, factors that can measure prognosis have not yet been identified due to considerable divergence among reports. Aim: To describe the computed tomography (CT) imaging, treatment, and outcomes of dogs with nasal tumors, as well as detect negative prognostic factors through the analysis of a substantial number of cases from a single institution. Furthermore, based on CT findings, this study aimed to identify independent prognostic factors for nasal tumors in dogs. Methods: A total of 166 client-owned dogs were diagnosed with nasal tumors at Gifu University Veterinary Hospital between 2015 and 2019. Data were retrospectively collected from the electronic medical records. Results: Univariate analysis revealed a significant difference in survival time between adenocarcinoma and squamous cell carcinoma in 166 canine nasal tumors treated with megavoltage (MeV) radiation therapy at a single institution (p = .015). There was a significant difference in survival time between carcinoma and sarcoma (p = .04). Regarding CT imaging findings, significant differences in survival time were observed for frontal sinus invasion (p = .007), cribriform plate destruction (p < .001), and lymph node metastasis (p = .003). Multivariate Cox regression analysis was performed to assess frontal sinus invasion, cribriform plate destruction, histopathologic subtypes, and lymph node metastasis as negative prognostic factors; however, only cribriform plate destruction was a significant negative prognostic factor for survival time (p = .004). Conclusion: Multivariate Cox regression analysis showed that cribriform plate destruction was the main factor in predicting a negative prognosis among 166 canine nasal tumors treated with MeV radiation therapy at a single institution. Therefore, we propose a new 2-tier staging classification for canine nasal tumors with the presence or absence of cribriform plate destruction based on CT examination as the only evaluation factor.

A case of olfactory ganglioneuroblastoma in a dog: immunohistochemical comparison with olfactory neuroepithelia and olfactory neuroblastomas.

In the present study, histopathological and immunohistochemical findings of olfactory ganglioneuroblastoma in a dog were compared to those of canine olfactory neuroepithelia and neuroblastomas. Olfactory ganglioneuroblastoma consists of ganglion cell-like tumor cells with Schwannian stroma and neuroblast-like tumor cells. Immunohistochemically, ganglion cell-like tumor cells were immunopositive for synaptophysin, ß3-tubulin, and tyrosine hydroxylase, Schwannian stroma was immunopositive for GFAP and SOX2, and neuroblast-like tumor cells were immunopositive for OLIG2, ß3-tubulin, SOX2, cytokeratin AE1/AE3, and p63. The immunohistochemical results of olfactory neuroepithelia and olfactory neuroblastomas were similar to those of neuroblast-like tumor cells. These results suggest that the ganglion cell-like tumor cells in the present case have a sympathetic neuron immunophenotype, whereas neuroblast-like tumor cells have an olfactory neuroepithelial immunophenotype.

Nasal clear cell chondrosarcoma in a dog.

An intranasal tumour was diagnosed in a 5-year-old male neutered crossbreed dog following a 6-8 week history of intermittent epistaxis and nasal discharge. Computed tomography identified a mass in the right nasal cavity. Histologically, the mass was composed of sheets and indistinct clusters of predominantly clear or vacuolated round to polygonal cells; periodic acid-Schiff staining revealed glycogen granules within some tumour cells. Immunohistochemical labelling revealed that the tumour cells were immunopositive for vimentin and S100 and negative for pancytokeratin, Melan-A and PNL2, supporting a diagnosis of a clear cell variant of chondrosarcoma (CCC). Although the dog was treated with meloxicam, the owners opted for euthanasia 9 days after presentation. Considering that there is only one other reported case of a suspected CCC in a dog, also in the nasal cavity, this could represent a species-specific predilection site of this rare canine neoplasm.

Description of outcome and adverse events in 21 cats with locally advanced nasal planum squamous cell carcinoma treated with electrochemotherapy.

OBJECTIVES: Squamous cell carcinoma (SCC) is the most common tumour in the nasal planum of cats. Surgery has traditionally been the treatment of choice but might not be feasible in locally advanced scenarios. Electrochemotherapy (ECT) has shown good control in superficial tumours, but there is a lack of robust information about efficacy in locally advanced cases. The aim of this study was to assess the safety and efficacy of ECT in the treatment of locally advanced stage nasal planum SCC in cats. METHODS: The clinical database of a veterinary referral hospital was searched retrospectively for cats diagnosed with a locally advanced nasal planum SCC (T3N0M0 or T4N0M0) that had received ECT. Local response, adverse events and outcome were documented. The data were evaluated by inferential statistics and correlations between response, recurrence, feline immunodeficiency virus/feline leukaemia virus status, number of treatments, voltage and severity of adverse events, with Kaplan-Meier curves and log-rank tests. Statistical significance was set at P <0.05. RESULTS: In total, 21 cats were enrolled over a 4-year period. Nineteen cats achieved a complete response (CR) and two cats a partial response (PR) for an overall response rate of 100%. Cats achieving a CR had a median disease-free interval of 182 days (range 128-327) and those with a PR had a median progression-free survival of 156.5 days (range 122-191). The median time to progression was not reached. The overall survival was 453 days for a median follow-up of 341 days (range 191-989). Of the cats, 62% had grade 3 or 4 toxicities, but no deaths due to the treatment were documented. Only voltage was correlated with longer survival (P = 0.001). CONCLUSIONS AND RELEVANCE: ECT appears to be an effective treatment for feline nasal planum SCC and could be considered a first-line therapy for locally advanced cases. Toxicities reported can be severe in the short term and these could be secondary to more invasive lesions and equipment used.

Nasal angioleiomyoma in 2 dogs.

This case report describes 2 dogs, an Appenzeller Mountain dog and an Irish Wolfhound, with angioleiomyoma within the nasal cavity. Endoscopic surgical resection resulted in cure in both dogs. Macroscopically and on diagnostic imaging, tumor masses may appear malignant because of local turbinate destruction. This highlights the importance of histological examination before any recommendations are made to owners because tumors of the nasal cavity may be benign and surgery curative.

Dorsal rhinotomy in a dog with a chondro-osseous respiratory epithelial adenomatoid hamartoma: a case report.

OBJECTIVE: To describe the clinical presentation, novel surgical approach, and outcome of a dog diagnosed with chondro-osseous respiratory epithelial adenomatoid hamartoma (COREAH). ANIMAL: 5-year-old castrated male Yorkshire Terrier. CLINICAL PRESENTATION, PROGRESSION, AND PROCEDURES: The dog was presented with chronic upper respiratory noise, congestion, facial swelling, ocular discharge, and an abscess on the nasal bridge. Two CT scans were performed 4 months apart. The CT scans yielded similar results: cyst-like nasal masses with severely destructive bilateral rhinitis with extensive polyostotic bony lysis. A dorsal rhinotomy with a turbinectomy and debridement of the nasal cavity were performed. A poorly defined but extensive lesion was found occupying the entirety of the left frontal sinus as well as the nasal cavity. TREATMENT AND OUTCOME: Histopathology revealed a mass consistent with COREAH. The dog recovered well from surgery, except for self-limiting subcutaneous emphysema, and 3 weeks postoperatively was reportedly doing well, with mild nasal discharge. Stridor, nasal discharge, and sneezing episodes were reported postoperatively; however, these were improved. At 18 months postoperatively, the dog died from uncontrolled seizures while hospitalized for suspected acute hemorrhagic diarrhea syndrome at a different hospital. CLINICAL RELEVANCE: COREAH should be considered a potential cause of destructive bilateral rhinitis and bony lysis in dogs. Dorsal rhinotomy can be a surgical treatment for dogs with possible COREAH with acceptable outcome, though complete remission of clinical signs may not be achieved. This is the first clinical description of COREAH in a dog.

[Nasal obstruction: Odontogenic cysts in 4 brachycephalic dogs]. / Nasale Obstruktion: Odontogene Zysten bei 4 brachyzephalen Hunden.

OBJECTIVE: Odontogenic cysts may be of developmental or inflammatory origin. They are frequently observed in brachycephalic dogs. Due to their expansive growth, cysts in the maxilla may extend into the nasal cavity, obstruct the nasal airway and cause nasal discharge. Epithelial cysts may lead to a comparable clinical picture. A new endonasal endoscopic intervention for the removal of these cysts is described. MATERIAL AND METHODS: Four brachycephalic dogs (Boxer, Chihuahua, French bulldog, Pug) with unilateral cysts obstructing the nasal cavity were included in the study. The animals underwent clinical examination, computed tomography (CT) imaging and rhinoscopy examination. Histopathologic evaluation of the cyst wall was performed. In addition to dental surgery and conventional extraction of the involved tooth, the cyst wall was removed by endoscopic intervention via the physiologic nasal opening. Clinical course following treatment was assessed by rhinoscopy and CT. RESULTS: The main clinical signs were unilateral or bilateral serous to hemorrhagic nasal discharge. Nasal airflow was restricted in all patients. Removal of the cysts and involved teeth did not lead to any intra- and postoperative complications. No recurrence of the cysts was observed. Histologic diagnosis consisted of an epidermoid cyst, a follicular cyst, a radicular cyst, and a canine odontogenic parakeratinized cyst (COPC). Neoplastic transformation was excluded in all cases. CONCLUSIONS: Removal of the cyst wall may be performed by means of minimally invasive endoscopic intervention via the physiologic nasal entrance. The procedure is curative and carries the risk of only few complications. In cases in which treatment is restricted to extraction of the affected tooth, the nasal airway may remain obstructed due to a calcified cyst wall. CLINICAL RELEVANCE: In brachycephalic dogs, oronasal defects due to dental pathology are the most common reason for chronic nasal discharge, whereas in normocephalic dogs nasal neoplasia are. Odontogenic cysts carry importance as differential diagnosis of nasal discharge.

Olfactory neuroblastoma in a domestic cat and review of the literature.

Nasal tumors account for less than 10% of all feline neoplasms, with lymphoma, followed by adenocarcinoma, and squamous cell carcinoma, the most commonly reported. Nasal neuroectodermal tumors, including olfactory neuroblastoma (ONB), are scarcely described, and their tumorigenesis is largely unknown. Here we report the cytological, histological, and immunohistochemical features of a feline ONB. We also provide a pathological review of nasal neuroendocrine neoplasms in cats. A 7-year-old Burmese cat was evaluated for sneezing, occasional epistaxis, and upper respiratory noise for 8 months. Computed tomography (CT) imaging revealed a 7 × 5 × 3 mm irregular mass effacing and expanding the nasal cavity, which extended to the nasopharynx. Cytologically, neoplastic cells were round to polygonal and had a round nucleus with finely stippled chromatin, a single small nucleolus, and abundant pale blue cytoplasm, which contained abundant fine pale pink granules. They exhibited mild cellular atypia, anisocytosis, and mild to occasionally moderate anisokaryosis. Rhinoscopic biopsies revealed a densely cellular, malignant neuroepithelial neoplasm. Cells were arranged in densely packed trabeculae and formed Homer Wright and Flexner-Wintersteiner-like rosettes, with rare mitotic figures and scant supportive fibrovascular stroma. Immunohistochemically, neoplastic cells were positive for vimentin, cytokeratin AE1/AE3, COX-2, and beta-tubulin and negative for S-100, chromogranin A, CD117, and epithelial membrane antigen (EMA). An ONB was diagnosed based on histological and immunohistochemical findings. Interestingly, and similar to nasal carcinomas, neoplastic cells diffusely neo-expressed COX-2. To the authors' knowledge, there is no previous evidence of COX-2 in feline ONB. Histopathology and immunohistochemistry are required for a definitive diagnosis of ONB.

Dynamic contrast-enhanced computed tomography in dogs with nasal tumors.

BACKGROUND: Treatment of nasal tumors in dogs is associated with high morbidity and reliable prognostic factors are lacking. Dynamic contrast-enhanced computed tomography (DCECT) can be used to assess tumor perfusion. OBJECTIVES: To assess perfusion parameters of nasal tumors (correlating with tumor type) before and during radiotherapy (RT) and find potential correlation with survival. ANIMALS: Twenty-four client-owned dogs with nasal tumors, including 16 epithelial tumors and 8 sarcomas. METHODS: Prospective cross-sectional study. All dogs had baseline DCECT to assess fractional vascular volume (BV), blood flow (BF), and transit time (TT). Thirteen dogs had repeat DCECT after 12 Gy of megavoltage RT. Survival times were calculated. RESULTS: Median BV was 17.83 mL/100 g (range, 3.63-66.02), median BF was 122.63 mL/100 g/minute (range, 23.65-279.99), and median TT was 8.91 seconds (range, 4.57-14.23). Sarcomas had a significantly lower BF than adenocarcinomas (P = .002), carcinomas (P = .01), and other carcinomas (P = .001), and significantly lower BV than adenocarcinomas (P = .03) and other carcinomas (P = .004). Significant associations were found between epithelial tumors and sarcoma for change in tumor volume (P = .01), width (P = .004), and length (P = .02) in that epithelial tumors decreased in volume whereas sarcomas increased in volume. Perfusion parameters were not correlated with survival. CONCLUSIONS AND CLINICAL IMPORTANCE: Nasal sarcomas have lower BV and BF than nasal carcinomas, and sarcomas have a lower size reduction than carcinomas early on during RT. Baseline results and changes in perfusion parameters may not be correlated with survival.

Assessment of the nasal microbiota in dogs with fungal rhinitis before and after cure and in dogs with chronic idiopathic rhinitis.

BACKGROUND: Pathogenesis of canine fungal rhinitis is still not fully understood. Treatment remains challenging, after cure turbinate destruction may be associated with persistent clinical signs and recurrence of fungal rhinitis can occur. Alterations of the nasal microbiota have been demonstrated in dogs with chronic idiopathic rhinitis and nasal neoplasia, although whether they play a role in the pathogenesis or are a consequence of the disease is still unknown. The objectives of the present study were (1) to describe nasal microbiota alterations associated with fungal rhinitis in dogs, compared with chronic idiopathic rhinitis and controls, (2) to characterize the nasal microbiota modifications associated with successful treatment of fungal rhinitis. Forty dogs diagnosed with fungal rhinitis, 14 dogs with chronic idiopathic rhinitis and 29 healthy control dogs were included. Nine of the fungal rhinitis dogs were resampled after successful treatment with enilconazole infusion. RESULTS: Only disease status contributed significantly to the variability of the microbiota. The relative abundance of the genus Moraxella was decreased in the fungal rhinitis (5.4 ± 18%) and chronic idiopathic rhinitis (4.6 ± 8.7%) groups compared to controls (51.8 ± 39.7%). Fungal rhinitis and chronic idiopathic rhinitis groups also showed an increased richness and α-diversity at species level compared with controls. Increase in unique families were associated with fungal rhinitis (Staphyloccaceae, Porphyromonadaceae, Enterobacteriaceae and Neisseriaceae) and chronic idiopathic rhinitis (Pasteurellaceae and Lactobacillaceae). In dogs with fungal rhinitis at cure, only 1 dog recovered a high relative abundance of Moraxellaceae. CONCLUSIONS: Results confirm major alterations of the nasal microbiota in dogs affected with fungal rhinitis and chronic idiopathic rhinitis, consisting mainly in a decrease of Moraxella. Besides, a specific dysbiotic profile further differentiated fungal rhinitis from chronic idiopathic rhinitis. In dogs with fungal rhinitis, whether the NM returns to its pre-infection state or progresses toward chronic idiopathic rhinitis or fungal rhinitis recurrence warrants further investigation.

A Combined Hypofractionated Volumetric Modulated Arc Radiotherapy, Radio-Sensitising and Adjuvant Metronomic Chemotherapy Treatment for Canine Stage IV Nasal Tumours With Intracranial Extension.

Radiation therapy has become the standard of care in the treatment of canine intranasal neoplasia, but because of the poor prognosis associated with stage IV nasal tumours and the proximity of the brain to the irradiation target, few data regarding the treatment of very advanced neoplasms are available. The aim of this pilot study was to evaluate the feasibility, safety and effectiveness of a combined treatment composed of definitive high-dose hypofractionated volumetric modulated arc radiotherapy on tumours with concurrent treatment of regional lymph nodes if positive or as prophylaxis, carboplatin radio-sensitising, and adjuvant metronomic chemotherapy for stage IV canine nasal tumours with intracranial extension. A pilot observational study was conducted in 7 dogs. Magnetic resonance imaging follow-up examinations revealed complete responses in 5 dogs and partial responses in 2. The median overall survival time, evaluated via Kaplan-Meier survival analysis, was 310 days with a 95% confidence interval of 210-400 days, whereas the median progression-free survival was 240 days with a 95% confidence interval of 190-290 days. Despite the proximity of highly sensitive organs at risk, no grade III or IV toxicities were observed, and volumetric modulated arc radiotherapy seemed to be a feasible treatment option for stage IV canine nasal tumours where conformal 3D radiotherapy has proven to give higher doses with severe damage to the surrounding unaffected tissues. Further studies are needed on the role of the sphenoid bone microscopic infiltration and regional lymph node involvement. The absence of severe toxicity could also lead to a dose escalation study and chemotherapy scheme.

Outcomes of megavoltage radiotherapy for canine intranasal tumors and its relationship to clinical stages.

Background: Radiation therapy is considered important for the treatment of intranasal tumors in dogs and is believed to be essential for prolonging their survival. Aim: To investigate the contribution of clinical staging to improve outcomes of megavoltage radiotherapy for canine intranasal tumors. Methods: A total of 123 dogs with intranasal tumors were included in the study. Forty-eight dogs received orthovoltage radiotherapy after cytoreductive surgery (Group I), 21 received orthovoltage radiotherapy without surgery (Group II), and 54 received megavoltage radiotherapy without surgery (Group III). All cases in each group were classified into clinical stages 1-4, and the median survival time (MST) was compared for each stage in all groups. Results: The overall MST was not significantly difference among Group I (325 days), Group II (317 days), and Group III (488 days); however, Group III was prolonged than Groups I and II. The MSTs for stages 1, 2, 3, and 4 were 597, 361, 267, and 325 days in Group I; 633, 260, 233, and 329 days in Group II; and 931, 860, 368, and 176 days in Group III, respectively. The MST for stage 2 cases in Group III was significantly prolonged when compared with that in Groups I and II; no significant difference was observed at other stages; however, the MST in Group III was longer in stage 1. These results showed that megavoltage radiotherapy prolonged the MST in dogs with intranasal tumors when compared to orthovoltage radiation with or without cytoreductive surgery, and that improvements in MST at stage 2 contributed significantly to this. Conclusion: The improvement in the MST in dogs with stages 1 and 2 intranasal tumors highlights the importance of starting megavoltage radiotherapy in the early stages.

Comparison of epidermal growth factor receptor (EGFR) and cyclooxygenase-2 (COX-2) immunohistochemical expression and outcomes in canine nasal carcinomas treated with radiation therapy.

The expression of epidermal growth factor receptor (EGFR) and cyclooxygenase-2 (COX-2) has been reported in human nasopharyngeal and canine nasal carcinomas. The present study measured EGFR and COX-2 expression and calculated correlations between these proteins and clinical variables and outcomes in dogs with nasal carcinoma treated with radiation therapy. Before treatment, the immunohistochemistry of EGFR and COX-2 was performed in 67 biopsied tissues from canine nasal carcinomas. The correlations between these protein levels, clinical variables, and outcomes were evaluated. EGFR and COX-2 were detected in 88.1% and 82.1% of our samples, respectively. Neither EGFR nor COX-2 was associated with T stage and cribriform plate destruction. Dogs with low EGFR levels had a significantly longer survival time than dogs with high EGFR expression (P=0.043). The COX-2 expression level was not significantly associated with survival times after radiation therapy (P=0.653). Overexpression of EGFR is negatively correlated with survival in dogs with nasal carcinoma. Future studies should identify tumor biomarkers to develop therapeutic targets for effective treatments for canine nasal carcinomas.

Dose- and Volume-Limiting Late Toxicity of FLASH Radiotherapy in Cats with Squamous Cell Carcinoma of the Nasal Planum and in Mini Pigs.

PURPOSE: The FLASH effect is characterized by normal tissue sparing without compromising tumor control. Although demonstrated in various preclinical models, safe translation of FLASH-radiotherapy stands to benefit from larger vertebrate animal models. Based on prior results, we designed a randomized phase III trial to investigate the FLASH effect in cat patients with spontaneous tumors. In parallel, the sparing capacity of FLASH-radiotherapy was studied on mini pigs by using large field irradiation. EXPERIMENTAL DESIGN: Cats with T1-T2, N0 carcinomas of the nasal planum were randomly assigned to two arms of electron irradiation: arm 1 was the standard of care (SoC) and used 10 × 4.8 Gy (90% isodose); arm 2 used 1 × 30 Gy (90% isodose) FLASH. Mini pigs were irradiated using applicators of increasing size and a single surface dose of 31 Gy FLASH. RESULTS: In cats, acute side effects were mild and similar in both arms. The trial was prematurely interrupted due to maxillary bone necrosis, which occurred 9 to 15 months after radiotherapy in 3 of 7 cats treated with FLASH-radiotherapy (43%), as compared with 0 of 9 cats treated with SoC. All cats were tumor-free at 1 year in both arms, with one cat progressing later in each arm. In pigs, no acute toxicity was recorded, but severe late skin necrosis occurred in a volume-dependent manner (7-9 months), which later resolved. CONCLUSIONS: The reported outcomes point to the caveats of translating single-high-dose FLASH-radiotherapy and emphasizes the need for caution and further investigations. See related commentary by Maity and Koumenis, p. 3636.

Outcome and complication rate of nasal planectomy reconstructed with direct mucocutaneous apposition.

Nasal planectomy is recommended in cases of squamous cell carcinoma of the nasal planum in dogs and can be curative if excision is complete. Due to the noticeable alteration in appearance inherent in nasal planectomy, several techniques are described for reconstruction. The goal of this study is to report the complication rate and owner satisfaction following nasal planectomy with repair by direct mucocutaneous apposition compared to other reported reconstruction techniques meant to be more cosmetic. Eleven dogs were identified that underwent nasal planectomy with reconstruction via mucocutaneous apposition. Complications were noted in 8/11 dogs: all minor. All dogs underwent CT preoperatively for surgical planning. Complete excision was noted in 10/11 cases. Results suggest that direct mucocutaneous apposition is a viable surgical option for reconstruction following nasal planectomy with favorable major complication rates and owner satisfaction. In addition, direct mucocutaneous apposition for closure following nasal planectomy should be considered, especially in cases in which bone is not resected, because of low complication rates and reasonable cosmetic outcome.

Résultat et taux de complications de la planectomie nasale reconstruite avec apposition cutanéomuqueuse directe. La planectomie nasale est recommandée en cas de carcinome épidermoïde du planum nasal chez le chien et peut être curative si l'exérèse est complète. En raison de l'altération notable de l'apparence inhérente à la planectomie nasale, plusieurs techniques sont décrites pour la reconstruction. Le but de cette étude est de rapporter le taux de complications et la satisfaction du propriétaire suite à une planectomie nasale avec réparation par apposition cutanéo-muqueuse directe par rapport aux autres techniques de reconstruction rapportées censées être plus esthétiques. Onze chiens ont été identifiés ayant subi une planectomie nasale avec reconstruction via apposition cutanéo-muqueuse. Des complications ont été notées chez 8/11 chiens : toutes mineures. Tous les chiens ont subi une tomodensitométrie préopératoire pour la planification chirurgicale. Une exérèse complète a été notée dans 10/11 cas. Les résultats suggèrent que l'apposition cutanéo-muqueuse directe est une option chirurgicale viable pour la reconstruction après une planectomie nasale avec des taux de complications majeures favorables et une satisfaction du propriétaire. De plus, l'apposition mucocutanée directe pour la fermeture après une planectomie nasale doit être envisagée, en particulier dans les cas où l'os n'est pas réséqué, en raison du faible taux de complications et du résultat esthétique raisonnable.(Traduit par Dr Serge Messier).

Single-modality palliative radiotherapy versus palliative radiotherapy after chemotherapy failure for cats with nasal lymphoma.

Published studies describing outcomes for cats with nasal lymphoma (NLSA) receiving first-line palliative radiation (PRT) versus PRT after chemotherapy failure are currently lacking. The aims of this retrospective observational study were to compare outcomes for cats with NLSA that were treated with these two methods. A total of 48 cats were included in analyses; 32 receiving PRT alone and 16 receiving PRT after chemotherapy failure. The treatment response, progression-free survival (PFS), disease-specific survival (DSS), overall survival (OS), and incidence rate of systemic disease were compared between the two groups. The overall response rate (ORR) was calculated from the same target lesions between pre-RT (within a week before starting PRT) and post-RT (on date of PRT completion) by computed tomography (CT) imaging. The ORR was 94% in cats that received PRT alone, 13 had a complete response (CR) and 17 had a partial response (PR). The ORR was 88% in cats that received PRT after chemotherapy failure, with five having CR and nine with PR. There were no significant differences in the ORR between the two groups. The PFS, DSS, and OS significantly increased in the cats that received PRT alone compared to the cats that received PRT after chemotherapy failure (median PFS: 336 vs 228 days, P = 0.0012, median DSS: 360 vs 242 days, P = 0.0025, median OS: 346 vs 242 days, P = 0.0036, respectively). The incidence rate of systemic disease significantly increased in 75% (12/16) of cats receiving PRT after chemotherapy failure compared to 41% (13/32) of cats receiving PRT alone. The results suggested that clinical outcomes may improve in cats with NLSA with first-line PRT compared to PRT after chemotherapy failure.

Outcome of stereotactic body radiation for treatment of nasal and nasopharyngeal lymphoma in 32 cats.

BACKGROUND: The safety and efficacy of stereotactic body radiation therapy (SBRT) in the treatment of localized nasal lymphoma in cats has not been described. HYPOTHESIS: Stereotactic body radiation therapy with or without adjuvant chemotherapy is an effective and well-tolerated treatment for localized nasal lymphoma in cats. ANIMALS: Thirty-two client owned cats referred to Colorado State University for the treatment of nasal lymphoma. METHODS: Retrospective study of cats treated with SBRT between 2010 and 2020 at Colorado State University. Diagnosis of nasal lymphoma was obtained via cytology or histopathology. Signalment, radiation protocol, concurrent treatments, adverse effects, and survival were recorded. RESULTS: Progression free survival was 225 days (95% CI 98-514) and median survival time (MST) was 365 days (95% CI 123-531). No significant difference in survival was identified between cats that received 1 versus greater than 1 fraction (MST 427 vs. 123 days, P = 0.88). Negative prognostic factors included cribriform lysis (MST 121 vs. 876 days, P = 0.0009) and intracalvarial involvement (MST 100 vs. 438 days, P = 0.0007). Disease progression was noted in 38% (12/32), locally in 22% (7/32), and systemically in 16% (5/32). No cats developed acute adverse effects. Ten cats developed late adverse effects: keratitis/keratitis sicca (n = 2), alopecia (n = 4), and leukotrichia (n = 4). Twenty-four cats (75%) had signs consistent with chronic rhinitis. CONCLUSIONS: SBRT is effective and well tolerated for treating localized nasal lymphoma in cats. Outcomes for cats with lower stage disease (canine modified Adam's stage 3 and lower) are comparable to historic data of cats treated with fractionated radiation therapy.

Re-irradiation of canine non-lymphomatous nasal tumours using stereotactic radiation therapy (10 Gy x 3) for both courses: Assessment of outcome and toxicity in 11 dogs.

No uniformly beneficial treatments exist for dogs with non-lymphomatous nasal tumours (NLNT) that relapse after radiotherapy (RT). Reirradiation may prolong survival and improve quality of life. In this retrospective study, we describe outcomes for 11 dogs that had CT-confirmed locoregional progression of NLNT after an initial course of stereotactic RT (SRT#1; 10 Gy × 3) and were then re-treated with the same type of protocol (SRT#2, also 10 Gy × 3). The median time between SRT #1 and SRT #2 was 243 days (95% CI: 78-385 days). Ten dogs (91%) had a clinical benefit after SRT#1; five dogs (45%) had clinical benefit after SRT#2. Adverse events after SRT#2 included nasocutaneous or oronasal fistula formation (N = 3 at 180, 270, and 468 days), seizures (N = 2 at 78 and 330 days), bacterial or fungal rhinitis (N = 2 at 240 and 385 days), and facial swelling (N = 1 at 90 days). All 11 dogs have died, due to disease progression, presumed radiotoxicity, or declining quality of life; in most cases, it was difficult to discern between these conditions. The median overall survival time (OST) from SRT#1 was 745 days (95% CI: 360-1132). The median overall survival time (OST) from SRT #2 was 448 days (95% CI: 112-626). For these dogs, survival was prolonged, but adverse events after SRT#2 were common (8/11; 73%). Therefore, before consenting to re-irradiation with this protocol, pet owners should be counselled about survivorship challenges, including risk for severe toxicities, and persistence of clinical signs.

A prospective, multi-centre, Veterinary Radiation Therapy Oncology Group study reveals potential efficacy of toceranib phosphate (Palladia) as a primary or adjuvant agent in the treatment of canine nasal carcinoma.

Radiation is the standard of care for dogs with nasal tumours. The addition of another therapy that could improve outcome without increasing toxicity is attractive. Medical therapy that could offer better outcome than maximally tolerated dose chemotherapy when radiation therapy (RT) is not possible or is declined is also attractive. This article reports the findings from a prospective, multi-centre, non-randomized, Veterinary Radiation Therapy Oncology Group clinical trial designed to evaluate whether toceranib phosphate (toceranib) has primary activity and if the addition of toceranib to RT could positively impact outcome. Owner's discretion determined enrolment in toceranib alone or toceranib + RT arm. Historical controls for radiation alone were selected from patients treated with identical RT and imaging protocols. Responses were evaluated with pre-treatment and week-16 CT scans. RT total dose of 42 Gy was completed in 10 fractions. Sixty-three dogs enrolled from 10 study sites. Overall response rates (CR + PR) were significantly improved in the toceranib + RT (79.4%) and RT alone (68.9%) arms over toceranib alone (22%) (p = .011). Clinical benefit rates (CR + PR + SD) were significantly improved in the toceranib + RT arm over the RT alone arm at 97.3% and 79.2% respectively (p = .036). Treatment with toceranib alone, toceranib + RT and RT alone resulted in median survival times of 298, 615 and 368 days respectively, but were not statistically significantly different (p = .0502). Adverse events associated with toceranib administration did not potentiate the RT side effect profile. Toceranib appears to have primary activity against nasal carcinoma.