Palliation of clinical signs in 48 dogs with nasal carcinomas treated with coarse-fraction radiation therapy

Advantages of the co2 laser use in the rare condition of nasal mucosa squamous cell carcinoma surgery in dogs-a clinical prospective study

Nasal mucosa tumors are an uncommon process and very dificult to work on with surgery. Radiotherapy associated or not with chemotherapy is the standard method to treat the disease. However, its access it is in the majority of the case not possible, making the surgery the best choice to try to achieve the patient's control. The anatomy of the region makes the complete surgical resection very difficult to achieve using the common and conventional blade scalpel surgery. The study features the advantages of using a CO2 laser to perform nasal mucosa carcinoma surgery in 6 dogs (N = 6). For the work we used an Aesculigth CO2 surgical laser model -Vetscalpel®, with the settings of 12Watts in a Superpulse mode, and a 0.25-0.4 mm focus to dissect the nasal mucosa, and a 1.5 mm focus for vaporization of the area. All the masses were histopathologically characterized as squamous cells carcinoma. The CO2 surgical laser allow us to work in a bloodless region promoting a more accurate dissection of the nasal mucosa sparing therefore the underlying and adjacent tissues and being less invasive. Also, it was possible to do the vaporization of the entire surgical area interviened. None of the patients presented relapse of clinical signs. Only 2 individuals were alive at the end of the study, presenting a survival rate of 420 and 514 days, which is in the same line of literature results of the treatment with radiotherapy combined with chemotherapy wich shows a median of 474-580 days. The study demonstrates successful outcomes with CO2 laser surgery in treating nasal mucosa SCC in dogs, with patients experiencing improved survival rates compared to traditional treatment methods. This highlights the efficacy and potential of CO2 laser surgery as a valuable tool in managing aggressive nasal tumors in veterinary oncology.

Description and efficacy of a response-based "QUAD" cyclical hypofractionated palliative-intent radiation protocol in dogs with macroscopic solid tumours: 108 cases

Palliative-intent radiation therapy can alleviate pain and clinical signs in dogs with cancer, but optimal fractionation scheme is unknown. The objective of this retrospective case series is to evaluate clinical benefit, objective response, adverse effects, and outcomes in 108 dogs with macroscopic solid tumours treated with a cyclical "QUAD" hypofractionated palliative-intent radiation therapy protocol. Median QUAD dose was 14 Gy (14-16 Gy). Median total dose was 28 Gy (14-48 Gy). Clinical benefit rate was 93%, with median onset of subjective palliation 21 days after the first QUAD, lasting a median of 134 days. Tumour volumetric objective response was assessed with CT prior to the third QUAD in 36 dogs, with stable disease in 24 dogs (67%) and partial response in 9 dogs (25%). Sinonasal and oral were the most common tumour locations in 32 and 30 dogs, respectively. Median progression-free survival was 153 days (95% CI 114-200). Median overall survival was 212 days (95% CI 152-259). Number of QUAD cycles completed, clinical benefit achieved, anti-inflammatory received, total radiation dose, time to maximum clinical benefit, and response duration were positively associated with progression-free and overall survival. Acute toxicities were observed in 15 dogs (14%) with 3 high-grade (grade 3) toxicities (3%). Low-grade (grade 1 and 2) late skin and ocular toxicities were observed in 31 dogs (29%), predominantly leukotrichia, alopecia, keratoconjunctivitis sicca, and cataracts. This report demonstrates that QUAD radiation is an alternative protocol to be considered for palliation of dogs with inoperable or advanced stage solid tumours.

Retrospective comparison of side effects and outcomes of three-dimensional conformal vs. intensity-modulated radiation therapy in the palliative-intent treatment (4 Gy × 5 daily fractions) of canine intranasal tumors (2010–2017)

Objective

To compare the occurrence of radiation side effects and treatment outcomes in dogs with intranasal tumors treated with a total dose of 20 Gy delivered in 5 daily 4 Gy fractions using computer-based 3D conformal (3DCRT) or intensity-modulated (IMRT) radiation therapy plans.

Design

Retrospective case series.

Materials and methods

Medical records for dogs with intranasal tumors treated with 4 Gy × 5 fractions between 2010 and 2017 were reviewed. Radiation side effects, time to local progression (TTLP), progression-free survival (PFS) and survival time (OS) were evaluated.

Results

Thirty-six dogs (24 carcinomas, 10 sarcomas and 2 others) met the inclusion criteria. Sixteen were treated with 3DCRT and 20 with IMRT. Clinical signs improvement or resolution were reported in 84% of dogs. The median time to clinical signs improvement was 12 days (1–88 days) after the end of treatment. Eight dogs treated with 3DCRT (8/16, 50%) and 5 with IMRT (5/20, 25%) were documented acute radiation side effects. Almost all were classified as grade 1 skin, oral or ocular acute side effects. Only one dog in 3DCRT group was demonstrated grade 2 skin acute effects. The median TTLP for dogs treated with 3DCRT or IMRT was 238 days and 179 days, respectively (p = 0.967). The median PFS for 3DCRT or IMRT was 228 days and 175 days, respectively (p = 0.940). The median OS for 3DCRT or IMRT was 295 days and 312 days, respectively (p = 0.787). No significantly differences were observed in side effects, TTLP, PFS and OS between 3DCRT and IMRT groups.

Conclusions

Palliative-intent conformal radiation therapy given in five daily 4 Gy fractions relieved clinical signs with minimal radiation side effects, with no statistical difference in occurrence between 3DCRT and IMRT dogs.

Frontal sinus carcinoma in forty-one dogs (2001-2022)

Reports on canine frontal sinus carcinomas (FSCs) are scarce. This retrospective review of 41 dogs with FSC (2001-2022) describes demographic and clinical characteristics of canine FSC and reports the clinical experience and overall survival following treatment with toceranib phosphate (TOC) and meloxicam in 10 cases. Median age at diagnosis was 10.6 years (range: 6.5-15.4 years). There was a male-to-female-ratio of 2.4:1. The most common breeds were Jack Russell Terriers (JRT) (n = 7; 17.1%) and Rottweilers (n = 3, 7.3%). Mesocephalic breeds (70.6%) were most commonly affected, brachycephalics accounted for 8.8%. The most frequent clinical signs included skull deformation dorsomedial to the eye (87.5%), pain/head-shyness (40.0%), ocular (22.5%)/nasal (17.5%) discharge, and exophthalmos (17.5%). Duration of symptoms prior to diagnosis varied from a few days to 9 months. There were no neurological signs at initial presentation despite imaging evidence of osteolysis of the lamina interna of the frontal bone in most dogs (69.4%). In 11.5%, pulmonary changes suggestive of metastasis or concurrent primary pulmonary neoplasia were present. Tumour types included squamous cell carcinoma (58.5%), unspecified carcinoma (29.3%), and adenocarcinoma (9.8%). Ten dogs were treated with TOC (median 2.8 mg/kg EOD or three times per week) and meloxicam (0.1 mg/kg, EOD) (TOC-M), resulting in subjective regression of skull deformity in 8/10 (80.0%) patients. Overall median survival time with TOC-M was 183.5 days (range: 120-434 days). FSCs typically present with skull deformation, but no overt neurological signs. Male dogs and JRT may be overrepresented. The use of TOC-M in FSC appears promising and warrants further prospective evaluation.

Pilot study evaluating the tolerability of a 3 Gy × 10 daily fraction 3D-conformal palliative radiation therapy protocol plus toceranib for the treatment of measurable carcinomas in the dog

The use of radiation therapy in conjunction with small molecule inhibitors is an appealing treatment combination for non-resectable carcinomas, which tend to be locally invasive with variable risk of locoregional metastasis. This prospective, pilot study aimed to evaluate the tolerability and adverse event profile of concurrent toceranib and palliative-intent radiation therapy (PRT) in dogs with measurable carcinoma and to secondarily evaluate short-term measurable tumor response. Fifteen dogs with measurable carcinoma received toceranib and 3D-conformal PRT in 3 Gy/fraction for 10 daily fractions. Adverse events were graded using standard schemes and tolerability was followed via quality-of-life questionnaires during the 12-week treatment period. Thirteen dogs (87%) experienced acute radiation toxicity, graded as severe in three dogs. All dogs experienced toceranib toxicity, graded as severe in one dog. Seven dogs (47%) completed the 12-week study protocol; four were withdrawn due to toxicity and/or associated poor quality of life and four developed progressive disease. Based on these preliminary results, this 3D-conformal chemoradiation protocol should be considered with caution and only with proper owner education on potential toxicity. More conformal treatment planning techniques or alternative protocols should be investigated for improved tolerability.

Treatment of advanced-stage canine nasal carcinomas with toceranib phosphate: 23 cases (2015-2020)

OBJECTIVE

To determine the median survival time (MST) of dogs with nasal carcinoma treated with toceranib phosphate.

MATERIAL AND METHODS

The databases of four Spanish referral hospitals were retrospectively searched for dogs with a diagnosis of nasal tumours presented between January 2015 and October 2020. Dogs treated with radiotherapy or other chemotherapies prior toceranib were excluded.

RESULTS

Twenty-three dogs with a confirmed nasal carcinoma treated with toceranib phosphate and with a CT scan for initial staging according to Adams Modified Staging System were included. Nine dogs had a stage III nasal carcinoma whereas 14 dogs had a stage IV nasal carcinoma. No dog had stages I and II nasal carcinoma. The median overall survival time was 139 days. The difference between the MST between dogs with stages III and IV was not statistically significant [P = 0.6, 140 days for stage III (range 46-401) vs 120 days for stage IV (range 23-600)]. Overall, dogs with epistaxis achieved a longer median survival (166 days) than dogs without epistaxis (83 days). Toceranib phosphate was generally well tolerated. Most dogs had an initial clinical benefit followed by progressive disease.

SIGNIFICANCE

This is the first study to report the MST in dogs with stages III and IV nasal carcinoma treated with toceranib phosphate. This retrospective study showed that toceranib phosphate decreases the clinical signs associated with nasal carcinomas.

A possible role of coarse fractionated radiotherapy in the management of gingival squamous cell carcinoma in dogs: A retrospective study of 21 cases from two referral centers in the UK

Surgery with or without the addition of radiotherapy is the treatment of choice for canine oral squamous cell carcinoma (SCC). Fractionated radiotherapy alone is also effective in the long-term control of the disease, however coarse fractionated radiotherapy (CF-RT) for gingival SCC has not been extensively reported. The aim of this study was to describe side effects, clinical response, and median survival time (MST) of dogs with gingival SCC treated with CF-RT in the palliative and adjuvant setting. Twenty-one cases from two referral centres in the UK treated with CF-RT for gingival SCC between July 2013 and June 2019 were retrospectively evaluated. Of the 21 dogs, 11 developed mild acute adverse effects. Oral mucositis was the most common radiation induced toxicity. Three dogs developed chronic severe adverse effects (oro-nasal fistula, bone necrosis and gum recession). Overall clinical response rate was 77% in dogs receiving palliative treatment with MST of 365 days (60-1,095 days). MST was not reached for dogs treated in the adjuvant setting with a mean of 466 days (121-730 days). In cases of advanced gross disease CF-RT might have a role in short term palliation of clinical signs. However, it carries a significant risk of late toxicity for cases with unexpectedly long survival times and further investigations are required to identify an optimal CF-RT protocol. Randomized controlled trials are needed to confirm the role of CF-RT as adjuvant treatment of incompletely resected gingival SCC.

Efficacy of chemotherapy and palliative hypofractionated radiotherapy for cats with nasal lymphoma

Nasal lymphoma (NL) is the most common nasal tumor in cats, and radiotherapy, chemotherapy, or a combination of these treatments have been described as the treatment for this disease. However, the previous studies included various machines and protocols of radiotherapy. Therefore, we aimed to retrospectively compare the prognosis among cases treated with palliative hypofractionated radiotherapy, chemotherapy, and a combination of them with united machine and protocol of radiotherapy. When compared overall survival and progression free survival, there was no significant difference among these three groups. The data of this study suggested that similar efficacy could be achieved by palliative hypofractionated radiotherapy, chemotherapy, or a combination of them.

Treatment of nasal tumours in dogs: a review

Nasal tumours are common neoplasms in dogs and often represent a diagnostic and therapeutic challenge due to their confined location within the nasal cavities. The main goal of this review is to extract the most relevant information from a wide and often confusing evidence-based medicine on the treatment of canine nasal tumours and conclude with current recommendations. This report highlights the different therapeutic modalities available and describes their technical aspects, interests and limitations. Megavoltage radiotherapy, as the most recent treatment and standard of care, is particularly examined, especially the different types of radiotherapy units, the main protocols used and their advantages and limits. Newer and non-conventional treatments are also discussed.

Ocular and periocular radiation toxicity in dogs treated for sinonasal tumors: A critical review

Visual impairment from radiation‐induced damage can be painful, disabling, and reduces the patient's quality of life. Ocular tissue damage can result from the proximity of ocular organs at risk to irradiated sinonasal target volumes. As toxicity depends on the radiation dose delivered to a certain volume, dose‐volume constraints for organs at risk should ideally be known during treatment planning in order to reduce toxicity. Herein, we summarize published ocular toxicity data of dogs irradiated for sinonasal tumors from 36 publications (1976‐2018). In particular, we tried to extract a dose guideline for a clinically acceptable rate of ocular toxicity. The side effects to ocular and periocular tissues were reported in 26/36 studies (72%) and graded according to scoring systems (10/26; 39%). With most scoring systems, however, toxicities of different ocular and periocular tissues are summed into one score. Further, the scores were mostly applied in retrospect and lack volume‐ and dose‐data. This incomplete information reflects the crux of the matter for radiation dose tolerance in canine ocular tissues: The published information of the last three decades does not allow formulating dose‐volume guidelines. As a start, we can only state that a mean dose of 39 Gy (given in 10 x 4.2 Gy fractions) will lead to loss of vision by one or both eyes, while mean doses of <30 Gy seem to preserve functionality. With a future goal to define tolerated doses and volumes of ocular and periocular tissues at risk, we propose the use of combined ocular toxicity scoring systems.

Retrospective survey of owners' experiences with palliative radiation therapy for pets

OBJECTIVE To describe animal owners' experiences with palliative radiation therapy (PRT) of pets and identify factors influencing satisfaction with their pets' treatment. DESIGN Retrospective, cross-sectional study. SAMPLE 118 owners of dogs, cats, or rabbits. PROCEDURES Medical records were searched to identify animals that underwent PRT between 2004 and 2013. Signalment, tumor-related data, and outcome information were recorded. Owners completed an electronic survey assessing satisfaction with treatment (ie, satisfaction with the decision for their pet to undergo PRT and indication that they would choose PRT for their pet again), expectations regarding PRT, and perceptions of their pets' quality of life (QOL) and signs of discomfort from acute adverse radiation effects. Additional data regarding practical aspects of treatment, pet death, communications with veterinarians, and owner demographics were collected. Variables were tested for association with measures of owner satisfaction. RESULTS 92 of 116 (79%) owners were satisfied with the decision to have their pets undergo PRT. Most (92/118 [78%]) owners reported their pet's QOL improved after PRT; these owners were significantly more likely to be satisfied than those who did not report improved QOL. Owners who perceived their pets had discomfort from adverse radiation effects (38/116 [33%]) were significantly less likely to be satisfied than owners who did not report this observation. Measures of satisfaction were not associated with patient survival time. Twenty-one of 118 (18%) owners indicated they expected PRT would cure their pet's tumor. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that short life expectancy should not deter recommendation of PRT for pets. Protocols that minimize risk of acute adverse effects may be advantageous. Veterinarians should attempt to ensure that owners understand the goals of PRT.

Private Practice Oncology: Viewpoint on End-of-Life Decision-Making

Veterinary oncology has evolved rapidly over the past 30 years, with combinations of surgery, chemotherapy, immunotherapy, and radiation therapy now representing standard practice for managing pets with cancer. Recently, additional effort has been directed toward optimizing palliative strategies for mitigating clinical signs associated with advanced-stage disease, thereby reducing patient morbidity as pet owners navigate end-of-life decision making. This is a multi-dimensional, individualized process, which demands attention to the primary neoplastic condition, concurrent diseases, and emotional needs of the family. An approach to oncologic referral and end-of-life care is described, with attention to the dynamics between oncologist, referring veterinarian, and client.

Prognostic significance of midline shift of the olfactory or frontal lobes of the brain in canine nasal carcinomas treated by palliative radiotherapy: a pilot study

Canine nasal carcinomas are often treated with radiotherapy. Presence of lysis of the cribriform plate by tumor invasion (stage 4 by modified Adams’s staging system) is a well-known prognostic factor. In this study, dogs with stage 4 disease were divided into two subgroups based on the presence or absence of midline shift of the olfactory or frontal lobes of the brain (Stage 4a: without presence of midline shift. Stage 4b: with midline shift). The median survival time of dogs with midline shift was significantly shorter than that of dogs without midline shift (64 vs. 208 days). Our results indicate that the finding of a midline shift might have a prognostic significance in dogs with nasal carcinoma treated with radiotherapy.

Combination of radiation therapy and firocoxib for the treatment of canine nasal carcinoma

Carcinomas represent two-thirds of canine nasosinal neoplasms. Although radiation therapy (RT) is the standard of care, the incidence of local recurrence following treatment is high. Cyclooxygenase-isoform-2 (COX-2) is expressed in 71-95% of canine nasal carcinomas and has been implicated in tumor growth and angiogenesis. Accordingly, COX-2 inhibition seems rational to improve outcome. Dogs with histologically confirmed, previously untreated nasal carcinomas were randomized to receive the combination of a selective COX-2 inhibitor (firocoxib) and palliative RT (Group 1) or RT and placebo (Group 2). Patients were regularly monitored with blood tests, urinalysis, and computed tomography. Pet owners were asked to complete monthly a quality-of-life questionnaire. Twenty-four dogs were prospectively enrolled. According to Adams modified system, there were five stage 1, five stage 2, three stage 3, and 11 stage 4 tumors. Two dogs had metastases to regional lymph nodes. Median progression-free interval and overall survival were 228 and 335 days in Group 1 (n = 12) and 234 and 244 days in Group 2 (n = 12). These differences were not statistically significant. The involvement of regional lymph nodes was significantly associated with progression-free interval and overall survival (P = 0.004). Quality of life was significantly improved in Group 1 (P = 0.008). In particular, a significant difference was observed for activity and appetite. Although not providing a significant enhancement of progression-free interval and overall survival, firocoxib in combination with RT is safe and improved life quality in dogs with nasal carcinomas.

Evaluation of outcomes and radiation complications in 65 cats with nasal tumours treated with palliative hypofractionated radiotherapy

Feline nasal tumours (NTs) are locally invasive and occasionally metastasise to distant sites. Although palliative hypofractionated radiotherapy (HRT) is used, its efficacy and long-term complications have not been adequately evaluated. The purpose of this study was to evaluate the efficacy of HRT in treating feline malignant NTs, including monitoring improvement in clinical signs, acute and late complications, and prognosis. The medical records of 65 cats with malignant NTs treated with HRT were included. Overall survival (OS) and progression-free survival (PFS) were calculated using the Kaplan-Meier method. The log-rank test and Cox proportional hazard model were used to evaluate factors that influenced OS and PFS. Clinical signs improved in 86.2% of cats following radiotherapy. Acute complications were observed in 58.5% of cats but were manageable and acceptable. Among late complications, cataract was most frequently observed (20.5%), and atrophy of the entire eyeball and osteochondroma at the irradiation site were each observed in two cats. The median OS and PFS in 65 cats were 432 days and 229 days, respectively. No significant difference between OS of cats with nasal lymphoma and that of cats with other tumours was observed. Despite some limitations due to the retrospective nature of the study, palliative HRT for feline NTs can be considered a useful treatment option because of the high incidence of improvement and more favourable prognosis, although it may be preferable not to use the hypofractionated regimen in young cats with lymphoma that are expected to survive for a long period.

Palliative radiation therapy outcomes for cats with oral squamous cell carcinoma (1999-2005)

Squamous cell carcinoma (SCC) accounts for approximately 10% of all feline tumors. The purpose of this retrospective study was to describe outcomes for a group of cats with oral SCC that were treated with palliative radiation therapy. Fifty-four cats met the inclusion criteria of nonresectable, oral SCC treated with coarse fractionated megavoltage (MeV) radiation therapy. Radiation therapy for all cats was delivered with a 6 MeV linear accelerator. Total radiation doses of 24 Gray to 40 Gray were administered in three to four fractions, once-per-week over 4 to 5 weeks. Concurrent chemotherapy protocols varied and were administered at the discretion of the clinician and client. Forty-nine patients completed the planned treatment protocols. Overall mean and median survival times for cats completing the planned treatment protocols were 127 and 92 days (n = 49). Mean and median survival times of cats receiving palliative radiation therapy alone were 157 and 113 days (n = 12). Mean and median survival times of patients receiving both radiation therapy and chemotherapy were 116 and 80 days (n = 37). Patients with sublingual tumors had a median survival time of 135 days (n = 15), compared to mandibular tumors that had a median survival time of 80 days (n = 26). For the majority of patients that completed the planned treatment protocol (65%), owners reported a subjectively improved quality of life. Findings from this uncontrolled study supported the use of palliative radiation therapy for cats with nonresectable oral squamous cell carcinoma.

Reirradiation of canine nasal carcinomas treated with coarsely fractionated radiation protocols: 37 cases

Data from 37 dogs with nasal carcinomas treated with two or more coarsely fractionated courses of radiation therapy (RT) were retrospectively reviewed. The median radiation dose for the first course of RT was 24 Gray (Gy). All dogs clinically responded, and 11 had complete resolution of signs for a median of 114 days. Dogs were retreated at relapse, with a median dose of 20 Gy, and 26 of 37 dogs (70%) had clinical responses. The second course of RT was initiated at a median of 150 days following completion of the first course. Side effects were mild: four dogs had chronic ocular conditions necessitating medication, one of which required enucleation. Median survival time (ST) from the first dose of RT was 453 days and 180 days from the first dose of the second course of RT. The following factors were examined but were not significant for survival: total RT dose, dose of the first course of RT, complete resolution of clinical signs, use of either chemotherapy or nonsteroidal anti-inflammatory drugs (NSAIDs), and stage (T1/T2 versus T3/T4). Dogs responded well to reirradiation with a subset experiencing chronic ocular side effects.

Late presentation of canine nasal tumours in a UK referral hospital and treatment outcomes

OBJECTIVES

To determine the computed tomographic stage of dogs with nasal tumours in a UK referral population, and whether stage, time to referral and treatment correlates with outcome.

METHODS

Retrospective review of clinical records and computed tomography scans of dogs with nasal tumours.

RESULTS

Dogs (n=78) presented to a referral practice in the UK with suspected nasal tumours are presented with more late stage tumours than dogs in the USA and Japan. Length of time from initial presentation to referral did not correlate with tumour stage at diagnosis. Median survival times for radiotherapy-treated dogs in this population are equivalent to those previously reported for late stage nasal tumours.

CLINICAL SIGNIFICANCE

Dogs with nasal tumours are presented late in the course of disease in the North West of England. Dogs with clinical signs consistent with a nasal tumour should have timely imaging and biopsy, in order to make prompt treatment decisions. Although survival times are comparable with previous reports and radiotherapy is a valid treatment option for dogs with late stage disease, better outcomes are likely to be achievable with earlier treatment.

Efficacy of hypofractionated radiotherapy for nasal tumours in 38 dogs (2005-2008)

OBJECTIVES

To evaluate the efficacy of hypofractionated radiotherapy for canine nasal tumours, including the improvement in clinical signs, rate of complications and assessment of prognostic factors.

METHODS

Medical records of 38 dogs with malignant nasal tumours were reviewed, and those treated with a weekly schedule of hypofractionated radiotherapy were included in the study. Acute and late side effects were defined as complications noted either within 1 month or after 6 months of irradiation, respectively. Progression-free interval and overall survival were calculated using the Kaplan-Meier method. Log-rank test and Cox proportional hazard model were also performed.

RESULTS

Clinical signs improved in 30 of 36 dogs. Acute complications were seen in 28 of 36 dogs and were considered manageable. Late complications were observed in 17 of 30 dogs that survived 6 months or longer, but severe side effects were not observed. The median progression-free interval and overall survival was 245 days (95% CI: 127-512 days) and 512 days (95% CI: 203-820 days), respectively. Age, breed and presence of dyspnoea were negatively correlated with overall survival.

CLINICAL SIGNIFICANCE

These results suggest that hypofractionated radiotherapy could be a viable option for the treatment of nasal tumours in dogs that are not candidates for conventional multi-fractionated radiotherapy.

Prospective evaluation of a 5 × 4 Gy prescription for palliation of canine nasal tumors

We evaluated the efficacy of palliative radiation therapy using 5 × 4 Gy given daily in 18 dogs with nasal tumors. Dogs with malignant nasal tumors were evaluated for response rate, response duration, and survival. Seventy-eight percent of the dogs achieved complete resolution of clinical signs, and 16.5% had partial resolution of their signs. Overall median response duration for all dogs was 178 days after one course of radiation therapy. Six dogs received a second course of therapy when their disease progressed using the same daily 5 × 4 Gy scheme, and all six responded for a median time of 129.5 days for an overall median survival time in these six dogs of 309 days. Based on these results, a radiation prescription of 5 × 4 Gy appears to be useful palliatively in dogs with a malignant nasal tumor.

Response rate and duration associated with a 4Gy 5 fraction palliative radiation protocol

The purpose of this retrospective study was to determine if 4Gy fractions over 5 consecutive days is an effective and safe palliative radiation protocol for dogs and cats. Eighty patients (22 cats, 58 dogs) with complete follow-up information were evaluated. Overall response rate (ORR) for all patients was 67%. Median progression free survival (MPFS) was 3.3 months and median survival (MST) was 4.2 months. Primary bone tumors were the most common tumors treated. The ORR for primary bone tumors was 66.6%, the MPFS was 3.5 months, and MST was 3 months. The most common tumor treated in cats was oral squamous cell carcinoma and ORR was 54.5 %, the MPFS was 1.8 months, and MST was 3 months. Soft tissue sarcomas were the second most common tumor treated in dogs (10). ORR was 80% and the two other patients had stable disease. MPFS was 5.7 months and MST was 7.9 months. Overall rate of toxicity was 18.4% in 65 sites that were evaluated for toxicity. Acute toxicities were all grade I or II and occurred in 16.9 % of patients evaluated. All late toxicity was grade I alopecia and leukotrichia. There appears to be a comparable response rate for this palliative protocol as compared to others historically. This response was seen over a wide range of tumors. We also documented a low toxicity profile in a shorter overall treatment time, making this protocol more attractive for some clients.

Radiotherapy-induced myelosuppression in dogs: 103 cases (2002-2006)

Definitive radiotherapy refers to delivery of large doses, typically 48-62 Gray, of ionizing radiation over several weeks using a daily or alternate-day fractionation schedule. The impact of definitive radiotherapy alone on haematopoiesis in tumour-bearing dogs is unknown. Medical records from 103 dogs receiving definitive (60) Cobalt teletherapy for cancer over a 5-year period were reviewed for signalment, tumour type and location, total radiotherapy dose and fractionation scheme. Complete blood count data were collected before, halfway through, and at the end of radiation treatment, and analysed for changes associated with patient variables. The results demonstrate significant reductions in haematocrit, total white blood cell count, neutrophils, eosinophils, monocytes, lymphocytes and platelets occurred during definitive radiotherapy but remained within laboratory reference intervals. These data are important for anticipation of toxicity associated with combinations of radiotherapy and chemotherapy in dogs but do not support the routine monitoring of haematology parameters during definitive radiotherapy.

Retrospective study of canine nasal tumor treated with hypofractionated radiotherapy

The object of this study was to evaluate hypofractionated multiportal field and two-portion (rostral and caudal portions divided by the eyelid) radiation therapy for canine nasal tumors. Sixty-three dogs underwent multiportal hypofractionated radiation therapy. The radiation field was divided into rostral and caudal portions by the eyelid. Treatments were performed four times for 57 dogs. The median irradiation dose/fraction was 8 Gy (range, 5-10 Gy); the median total dose was 32 Gy (10-40 Gy). Improvement of clinical symptoms was achieved in 53 (84.1%) of 63 cases. Median survival time was 197 days (range, 2-1,080 days). Median survival times with and without destruction of the cribriform plate before radiotherapy were 163 and 219 days, respectively. There was no significant difference between them. No other factors were related to survival according to a univariate analysis. All radiation side effects, except one, were grade I according to the VRTOG classification. It was not necessary to treat any dogs for skin side effects. One dog (1.6%) developed an oronasal fistula 1 year after completion of radiation therapy. This radiation protocol may be useful in reducing radiation side effects in dogs with cribriform plate destruction.

COX-2 expression and outcome in canine nasal carcinomas treated with hypofractionated radiotherapy

The expression of cyclooxygenase isoform 2 (COX-2) in canine nasal carcinomas has been well documented. COX-2 expression has proven to be a prognostic factor in several human tumours. The aims of this study were to assess the correlation between immunohistochemical COX-2 expression and prognosis using rhinoscopic biopsies from 42 dogs with nasal carcinomas treated with hypofractionated radiotherapy, and to establish a replicable COX-2 scoring system. Ninety per cent of sections evaluated were COX-2 positive with a mean score of 6.6 (median 8.0; range 0-12). Neither COX-2 expression nor tumour type had a significant correlation with survival. There are likely to be many as yet unidentified variants which contribute to length of survival in dogs with nasal carcinomas. Immunohistochemical COX-2 expression appears unlikely to be of prognostic significance for canine nasal carcinoma.

3D conformal radiation therapy for palliative treatment of canine nasal tumors

We evaluated the response of 38 dogs treated with a coarsely fractionated, palliative radiation protocol based on CT-based 3D treatment planning. Dogs with histologically confirmed malignant nasal tumors were studied. Treatment prescriptions consisted of 3-4 x 8 Gy, 4-5 x 6 Gy, or 10 x 3 Gy fractions. Selected patient and tumor factors were evaluated for an effect on outcome. Resolution of clinical signs was reported after irradiation in all dogs. Acute toxicities were mild and short lived. Thirty-seven of 38 dogs died or were euthanized due to tumor-related disease. Overall median progression-free interval (PFI) was 10 months. Tumor stage affected response, with modified stage 1 patients having a median PFI 21.3 months vs. a median PFI of 8.5 months for modified stage 2 patients (P = 0.0006). Modified stage was the only factor significantly related to outcome. Based on these findings, a palliative radiation prescription based on computerized treatment planning may be justified in some canine nasal tumor patients.

Prognostic significance of specific magnetic resonance imaging features in canine nasal tumours treated by radiotherapy

OBJECTIVES

To investigate the prognostic significance of the magnetic resonance (MR) findings of meningeal hyperintensity of the olfactory bulbs and tumour extension into the caudal nasal recess (CNR) in dogs with nasal tumours treated by radiotherapy.

METHODS

MR images of 41 dogs with nasal tumours treated with radiotherapy were reviewed. The occurrence of neurological signs and survival of patients with and without meningeal hyperintensity of the olfactory bulbs and tumour extension into the CNR were analysed together with possible confounding factors including intracranial extension and patient age.

RESULTS

There was no significant association between the presence of meningeal hyperintensity or CNR involvement and the occurrence of neurological signs. Although there was a tendency towards shorter survival in dogs with tumour extension into the CNR, multivariable analysis showed no significant difference in survival between dogs with/without CNR involvement, meningeal hyperintensity or intracranial tumour extension (P=0.12, 0.50 and 0.57, respectively).

CLINICAL SIGNIFICANCE

In dogs with nasal tumours treated with radiotherapy, tumour extension into the cranium is not necessarily associated with shorter survival in patients without neurological signs at time of diagnosis. Although a definite influence of CNR involvement on case outcome could not be demonstrated, studies with a larger population are warranted.