Safety of alternate-day treatment with TS-1TM (tegafur/gimeracil/oteracil) in tumor-bearing dogs: a pilot study

Tegafur is a prodrug of fluoropyrimidine 5-fluorouracil (5-FU), while TS-1^TM is an oral fixed-dose combination of three active drugs, tegafur, gimeracil, and oteracil. This pilot study evaluated the safety of tegafur/gimeracil/oteracil in the treatment of cancers in dogs. Tegafur/gimeracil/oteracil was administered orally at a mean dose of 1.1 mg/kg twice daily on alternate days, Monday-Wednesday-Friday, every week to 11 dogs with tumors. Partial response and stable disease were observed in one dog each, whereas six exhibited progressive disease. Three dogs were not assessed. Adverse events, the most serious being grade 2, were noted in seven dogs. Adverse events were acceptable, and the drug was effective in some dogs. Therefore, tegafur/gimeracil/oteracil may be useful for treating malignant solid tumors in canines.     

High-dose-rate brachytherapy for intranasal tumours in dogs: results of a pilot study

This prospective study describes the feasibility and toxicity of ¹⁹²Iridium high‐dose‐rate (HDR) brachytherapy as an alternative strategy for the treatment of canine intranasal tumours. Fifteen dogs with malignant intranasal tumours were treated twice weekly using a hypofractionated protocol with eight fractions, 5 Gy per fraction, resulting in a total dose of 40 Gy. Acute and chronic adverse side‐effects appeared to be rare. Only 7% of the acute side‐effects and 5% of the chronic were classified as severe (grade 3). Eight dogs showed clinical complete remission, and five dogs had partial remission, with a resolution of tumour‐related symptoms. Magnetic resonance imaging showed a reduced tumour mass in 12 cases. Median survival time was 17 months (range 4–48 months), with four dogs (three without disease) still alive. Median time to recurrence of these dogs was 14 months. In nine dogs, progression or recurrence of the tumour was the cause of death. This study suggests that HDR brachytherapy is feasible and well tolerated.     

Evaluation of prognostic indicators in dogs with multiple,simultaneously occurring cutaneous mast cell tumours: 63 cases

Sixty‐three dogs with multiple contemporaneous cutaneous mast cell tumours (MCTs) were identified. The aim of this study was to determine the significance of breed, concurrent dermatological condition; number of cutaneous MCTs, size, location, histological grade and mitotic index; completeness of excision (complete, close or incomplete); local recurrence, metastasis and adjuvant therapy for the prognostic evaluation of dogs with a unique disease presentation of multiple, simultaneously occurring cutaneous MCTs. On the basis of multivariable survival analysis, dogs with one recorded grade 3 MCT had shorter progression‐free survival (PFS) times (18.7 versus 2.2 months) and median survival times (MSTs) (24 versus 3 months). Dogs treated with adjuvant vinblastine/lomustine had a 16 times increased risk of dying. MSTs were found to be significantly longer in dogs with one recorded MCT on an extremity. For all dogs, the PFS (range 14–1835 days) and MSTs (range 28–1835 days) were not reached.     

Use of indirect lymphography to identify sentinel lymph node in dogs: a pilot study in 30 tumours

This study reports the clinical value of sentinel lymph node (SLN) mapping with indirect lymphography (IL) using iodized oil (IO) as a marker injected preoperatively around the site of the primary tumour and radiography or tomodensitometry for imaging. Surgical extirpation of the node was performed following peritumoural injection of methylene blue (MB). Twenty nine dogs affected by 30 palpable solid tumours were prospectively studied. SLNs were identified by IL in 96.6% of the IL studies. IL followed by MB studies were performed in 25 dogs (26 studies). In these studies, agreement between IL and MB was observed in 84.6%. One dog had a minor complication following IO injection. This protocol represents an attractive alternative to scintigraphy for SLN mapping. This less technically demanding protocol may provide a wider access to SLN identification for application in veterinary oncology.     

Retrospective outcome evaluation for dogs with surgically excised,solitary Kiupel high‐grade,cutaneous mast cell tumours

Published outcomes for dogs with specifically high‐grade mast cell tumours (MCTs), controlled for clinical stage, are few. Clinical outcomes for 49 dogs with Kiupel high‐grade, clinical stage I, cutaneous MCTs were evaluated. Median survival time (MST) was 1046 days; 1 and 2‐year survival rates were 79.3% and 72.9%, respectively. At study end 24 dogs had died, 23 dogs were alive (median follow‐up 980 days) and 2 dogs were lost to follow‐up. Death was considered MCT‐related in 14 of 20 dogs with a known cause of death. Local tumour recurrence developed in nine dogs (18.4%); regional lymph node metastasis occurred in six dogs (12.2%); and a new MCT developed in 15 dogs (30.1%). Tumour location, histologic margin size and use of chemotherapy did not affect MST; increasing mitotic count (P = .001) and increasing tumour diameter (P = .024) were independently negatively prognostic. Six dogs that developed lymph node metastasis after surgery had worse MST (451 days) than 42 dogs that did not develop metastasis (1645 days); (P < .001). Our study suggests that dogs with local surgical control of clinical stage I histologically high Kiupel grade cutaneous MCT may have a long survival time; especially those with smaller tumours and a lower mitotic count. Our results suggest that evaluation of staging information and mitotic count may be equally helpful as histologic grading when making a prognosis; and highlight the importance of not relying on histologic grade alone when predicting survival for dogs with MCT.     

Long-term postsurgical outcomes of mast cell tumors resected with a margin proportional to the tumor diameter in 23 dogs

We evaluated the postsurgical outcomes of cutaneous or subcutaneous mast cell tumors (MCTs, n=25) in 23 dogs, resected with lateral surgical margins proportional to the widest tumor diameter, including at least one facial plane. The tumor diameter range was 0.3–2.6 cm (median: 0.9 cm), and all were histologically diagnosed as Kiupel’s low-grade MCT. Resection was histologically complete in 20, close (deep margin) in three, and incomplete (deep margin) in two. No dogs developed local recurrence at the site of initial surgery during follow-up of 161–2,219 days (median: 976 days). These results suggest that resection of low-grade, relatively small MCTs with surgical margins proportional to the tumor diameter is a practical procedure with high success rates.     

Serum neopterin, sialic acid and nitric oxide levels in dogs with malignant mammary tumours

Mammary cancer is one of the leading causes of death in pet population. Early diagnosis and malignancy detection is important for prognosis. The levels of neopterin, sialic acid and nitric oxide in serum of dogs with malignant mammary tumours were evaluated to investigate the importance of these biochemical parameters for malign mammary tumour. Twelve healthy dogs and twenty dogs with malignant mammary tumours were used as research materials. Blood samples were collected from both groups for neopterin analysis by enzyme-linked immunosorbent assay, whereas nitric oxide and sialic acid were measured by modified nitrate reductase method and spectrophotometry, respectively. Tissue specimens were evaluated and defined as malignant tumours. Serum nitric oxide and sialic acid levels in dogs with mammary tumours were significantly higher than those in the healthy dogs. Serum neopterin levels were not found significantly different in dogs with mammary tumours compared to healthy dogs. Malignancy of canine mammary tumours are accompained by an elevation of nitric oxide and sialic acid levels.     

Morphometrical approach for predicting regional lymph node micrometastatic load in canine mast cell tumours: preliminary results

Canine cutaneous mast cell tumours (MCTs) have a variable biologic behaviour, and accurate staging is necessary to dictate therapy and predict outcome. Regional lymph node (RLN) involvement is a relevant prognostic factor. While obvious lymph node (LN) metastases are relatively easy to be diagnosed, micrometastatic disease recognition is challenging. The main aim of the study was to evaluate the number of mast cells (MCs) in the LNs of clinically healthy dogs ( n = 4, group 1), dogs with inflammatory diseases ( n = 31, group 2) and dogs with cutaneous MCT ( n = 27, group 3), including animals with no RLN metastases (subgroup 3.1), those with occasional MCs in RLNs (3.2) and those with obvious RLN metastasis (3.3). MCs also were morphometrically evaluated for the following nuclear parameters: mean nuclear area (MNA), mean nuclear perimeter (MNP), largest to smallest diameter length (LS ratio), mean nuclear form factor and coefficient of variation of nuclear area. The average percentages of MCs were 0.0 and 0.01 in groups 1 and 2, respectively, and 0.07, 2.4 and 47.1 in subgroup 3.1, 3.2 and 3.3. MNA and MNP were significantly higher in subgroup 3.3 than in group 2 ( P < 0.05). MNA and MNP in subgroup 3.2 suggested the presence of neoplastic MCs; this prediction of micrometastatic load correlated with outcome. Analysis of preliminary results shows that nuclear morphometry is useful to detect micrometastatic disease in RLN of dogs bearing cutaneous MCTs.     

Diagnostic accuracy of pre‐treatment biopsy for grading cutaneous mast cell tumours in dogs

Mast cell tumours (MCTs) are common tumours of the canine skin, and are estimated to represent up to 20% of all skin tumours in dogs. Tumour grade has a major impact on the incidence of local recurrence and metastatic potential. In addition to helping the clinician with surgical planning, knowledge of the tumour grade also assists in proper prognostication and client education. For pre‐treatment biopsies to be useful, there must exist a high level of correlation between the histopathological grade obtained from the pre‐treatment biopsy and the actual histopathological grade from the excisional biopsy. The aim of this study was to determine concordance of tumour grade between various biopsy techniques (wedge, punch, needle core) and the “gold standard” excisional biopsy method. We found an overall concordance rate of 96% based on the Patnaik grading system, and an overall concordance rate of 92% based on the Kiupel grading system. The accuracy of the various biopsy techniques (wedge, punch and needle core) when compared with excisional biopsy was 92%, 100% and 100%, respectively, based on the Patnaik grading system, and 90%, 95% and 100%, respectively, based on the Kiupel grading system. Of the cases with discordant results, the pre‐treatment biopsies tended to underestimate the grade of the tumour. Based on these results, we conclude that pre‐treatment biopsies are sufficiently accurate for differentiating low‐grade from high‐grade MCTs, regardless of biopsy technique or tumour location.     

Pre-operative neoadjuvant vinblastine-prednisolone in canine mast cell tumours: A single-centre retrospective cohort study

Neoadjuvant chemotherapy can be used in canine mast cell tumours (MCTs) to optimise surgical margins or to enable marginal excision in challenging locations. The objective of this study was to describe the outcome of dogs with cutaneous and subcutaneous MCTs treated with neoadjuvant vinblastine-prednisolone (NA-VP). Records of treatment-naïve dogs with cutaneous/subcutaneous MCT that received NA-VP were reviewed including signalment, indication for NA-VP, staging results, clinical response, surgical data and histopathology reports. For dogs with post-operative follow-up ≥365 days, predictive factors for local recurrence (LR) were evaluated. Forty-four dogs were included. NA-VP was indicated to optimise surgical margins (group MARG) in 19 dogs (43.2%) and to enable surgery (group MORB) in 25 dogs (56.8%). Complete and partial response were documented in 40.9% of dogs and 30 dogs (68.2%) underwent surgery. The indication for NA-VP was significantly associated with undergoing surgery (p < .001) on multivariable analysis. Twelve (48%) and 18 dogs (94.7%) underwent surgery in the group MORB and MARG, respectively. Five dogs (16.7%) experienced wound dehiscence. Complete excision was achieved in 14 dogs (46.7%). In dogs undergoing surgery with ≥365 days of follow-up, LR was documented in five cases (20.8%). None of the factors analysed including mitotic count, completeness of excision and response to NA-VP were associated with LR; notably, LR occurred in 3/11 (27.2%) completely excised MCTs. In a pre-operative setting, NA-VP appears safe and could be beneficial in selected cases. Prognostic factors such as clinical response, mitotic count and completeness of excision should be interpreted with caution following NA-VP.     

Oncolytic reovirus therapy: Pilot study in dogs with spontaneously occurring tumours

Oncolytic virotherapy is a novel treatment involving replication‐competent virus in the elimination of cancer. We have previously reported the oncolytic effects of reovirus in various canine cancer cell lines. This study aims to establish the safety profile of reovirus in dogs with spontaneously occurring tumours and to determine a recommended dosing regimen. Nineteen dogs with various tumours, mostly of advanced stages, were treated with reovirus, ranging from 1.0 × 10⁸ to 5.0 × 10⁹ TCID₅₀ given as intratumour injection (IT) or intravenous infusion (IV) daily for up to 5 consecutive days in 1 or multiple treatment cycles. Adverse events (AEs) were graded according to the Veterinary Cooperative Oncology Group‐ Common Terminology Criteria for Adverse Events (VCOG‐CTCAE) v1.1 guidelines. Viral shedding, neutralizing anti‐reovirus antibody (NARA) production and immunohistochemical (IHC) detection of reovirus protein in the tumours were also assessed. AE was not observed in most dogs and events were limited to Grade I or II fever, vomiting, diarrhoea and inflammation of the injected tumour. No infectious virus was shed and all dogs had elevated NARA levels post‐treatment. Although IHC results were only available in 6 dogs, 4 were detected positive for reovirus protein. In conclusion, reovirus is well‐tolerated and can be given safely to tumour‐bearing dogs according to the dosing regimen used in this study without significant concerns of viral shedding. Reovirus is also potentially effective in various types of canine tumours.     

Significant association of serum autoantibodies to TYMS,HAPLN1 and IGFBP5 with early stage canine malignant mammary tumours

Canine mammary tumours (CMTs) are the most prevalent neoplasms in female dogs. Despite the high incidence of such tumours, a lack of easily accessible biomarkers still impedes early diagnosis of malignant CMTs. Herein we identify thymidylate synthetase (TYMS), hyaluronan and proteoglycan link protein 1 (HAPLN1) and insulin‐like growth factor‐binding protein 5 (IGFBP5) as CMT antigens eliciting corresponding autoantibodies in CMT cases. We establish enzyme‐linked immunosorbent assays (ELISAs) to detect autoantibodies to TYMS (TYMS‐AAb), HAPLN1 (HAPLN1‐AAb) and IGFBP5 (IGFBP5‐AAb) in sera from 81 dogs with malignant CMTs (41 in Stage I), 24 with benign CMTs and 35 healthy controls. Levels of all the three autoantibodies are elevated in the malignant group compared with the healthy or the benign group; notably, the elevated autoantibody levels significantly correlate with the stage‐I CMTs. For discriminating malignant CMTs from healthy control, the area under curve (AUC) of TYMS‐AAb is 0.694 with specificity of 82.9% and sensitivity of 50.6%. The AUC of utilising HAPLN1‐AAb for distinguishing the stage‐I CMTs from healthy controls is 0.711 with specificity of 77.1% and sensitivity of 58.5%. In differentiating malignant CMTs from the benign, the AUC of IGFBP5‐AAb reaches 0.696 with specificity of 70.8% and sensitivity of 67.9%, and a combination of IGFBP5‐AAb and TYMS‐AAb increases the AUC to 0.72. Finally, the AUC of combined HAPLN1‐AAb and IGFBP5‐AAb in discriminating the stage‐I CMTs from the benign achieves 0.731. Collectively, this study highlights a significant association of the three serum autoantibodies with early stage malignant CMTs.     

Ultrasound is a poor predictor of early or overt liver or spleen metastasis in dogs with high‐risk mast cell tumours

Conflicting evidence exists regarding the importance of routine abdominal ultrasound (US) with hepatic and splenic fine needle aspiration (FNA) cytology during staging of canine mast cell tumours (MCT). The objective of this study was to correlate ultrasonographic and cytologic findings in dogs with strictly defined high‐risk MCTs and to determine the influence on outcome. Our hypothesis was that US poorly predicts visceral metastasis in high‐risk MCTs and that early metastasis is associated with improved outcome when compared to overt metastasis. US of liver and spleen correlated to cytologic results, categorized as no metastasis, early metastasis or overt metastasis. Of 82 dogs prospectively enrolled, 18% had early visceral metastasis and 7% had overt metastasis on cytology; 67% with visceral metastasis had regional LN metastasis. US was a poor predictor of metastasis with sensitivity, specificity, positive predictive value and negative predictive value for the spleen of 67%, 68%, 21% and 94%, respectively and for the liver of 29%, 93%, 56% and 82%, respectively. Median time to progression (TTP) for dogs with no metastasis, early metastasis and overt metastasis was not reached, 305 and 69 days, respectively (P < .001). Median survival time (MST) for the 3 groups were not reached, 322 and 81 days, respectively (P < .001). High Patnaik or Kiupel grade, early metastasis, overt metastasis and adequate local control were significantly associated with outcome. Early visceral metastasis was associated with poorer outcome compared to dogs without metastasis, however, a subset of dogs experienced long‐term control.     

Canine paediatric oncology: retrospective assessment of 9522 tumours in dogs up to 12 months (1993-2008)

Little information is available on the occurrence of neoplasms in dogs up to the age of 12 months. This is a retrospective review of histopathological diagnoses of neoplasia in dogs up to the age of 12 months based on biopsy specimens submitted to a commercial veterinary diagnostic laboratory in the United Kingdom between 1993 and 2008. In 20 280 histological submissions, 9522 neoplasms were identified. Canine cutaneous histiocytoma (n = 8465; 89%) was the most common histological type. Neoplasms other than histiocytoma (n = 1057; 11%) were grouped as benign epithelial (n = 375; 4%), haematopoietic (n = 229; 2%), benign mesenchymal (n = 145; 2%), miscellaneous (n = 118; 1%), non-hematopoietic malignant mesenchymal (n = 118; 1%) or malignant epithelial tumours (n = 72; <1%). Excluding canine cutaneous histiocytoma, 52% of tumours (n = 547) were benign, and 66% were from the skin or soft tissues. These data provide valuable epidemiological information on neoplasms occurring in juvenile dogs in the United Kingdom.     

Canine pancreatic islet cell tumours secreting insulin‐like growth factor type 2: a rare entity

Insulin‐like growth factor type II (IGF‐II) is the main cause of non‐islet cell tumour hypoglycaemia (NICTH) and insulin is thought to be the only factor causing hypoglycaemia in insulinomas. However, two case reports of pancreatic neuroendocrine tumours (PNETs) producing IGF‐II have been previously published: a human and a canine patient. In this study, we investigated clinical, histopathological, immunohistochemical and ultrastructural features, and biological behaviour of canine pancreatic IGF‐II‐omas, a subgroup of PNETs that has not been previously characterized. Case records of 58 dogs with confirmed PNETs and hypoglycaemia were reviewed: six patients were affected by IGF‐II‐omas. Surgery was performed in all cases and two dogs had metastases. Four patients remained alive and in remission at 370, 440, 560 and 890 days post‐diagnosis; two died of non‐tumour‐related causes. IGF‐II‐omas can be differentiated from insulinomas through hypoinsulinaemia, IGF‐II positive and insulin negative immunostaining. The prevalence of this neoplasia is low, accounting for just 6% of PNETs.     

Cytological lymph node evaluation in dogs with mast cell tumours: association with grade and survival*

The purpose of this retrospective cohort study is to describe the association of cytological assessment of lymph node metastasis with survival and tumour grade in dogs with mast cell tumours. Regional lymph node aspirates of 152 dogs diagnosed with a mast cell tumour were reviewed and classified according to specific cytological criteria for staging. 97 dogs (63.8%) had stage I tumours, and 55 (36.2%) had stage II tumours. Stage II dogs had a significantly shorter survival time than dogs with stage I disease (0.8 and 6.2 years, respectively; P < 0.0001). Dogs with grade III mast cell tumours were more likely to have stage II disease (P = 0.004). These results suggest that cytological evaluation of lymph nodes in dogs with mast cell tumours provides useful and valuable clinical information, and the results correlate with tumour grade and outcome thus providing a practical and non‐invasive method for staging.     

Sentinel lymph node mapping with computed tomography lymphography for mast cell tumours and a comparison between regional and sentinel lymph node histological status: Sixty-two cases

It is known that the regional lymph node (RLN) may not correspond to the sentinel lymph node (SLN) (the first lymph node draining the tumour), and many diagnostic techniques have recently been aimed at its detection. Although lymphoscintigraphy is the gold standard in both human and veterinary medicine for SLN mapping, it is relatively unavailable in veterinary medicine due to costs and difficult management of the radiotracer. This prospective study evaluated, as a first aim, the feasibility and sensitivity of the computed tomography lymphography (CTL) in detecting the SLN in 62 mast cell tumours (MCTs). The second aim was to evaluate the accuracy of the CTL in identifying the most representative lymph node of the patient's lymphatic status; the histological status of the SNL was compared with that of the RLN, to see in how many cases the patient's stage would have changed according to the RLN. When the RLN turned out to be also the SLN it was decided to excise, as a control LN, the one localised in the neighbourhood of the MCT (neighbouring lymph node; NLN). The detection rate was 90%, with failure of SLN identification in six cases. In 18 (32%) of 56 MCTs with a diagnostic CTL, the SLN did not correspond to the RLN. Forty-five MCTs were surgically removed, together with their corresponding SLN and RLN/NLN. Since the clinical stage of the patient would have changed in only 7% of cases, CTL is a reliable method of detecting the SLN and, for staging purposes, there is no need to remove other LNs.     

Retrospective analysis of outcome and prognostic factors of subcutaneous mast cell tumours in dogs undergoing surgery with or without adjuvant treatment

Subcutaneous mast cell tumours (SC MCTs) can display a different biological behaviour in dogs when compared to their cutaneous counterpart. There is a paucity of information with regards to the outcome of dogs with SC MCTs treated with surgery and/or receiving adjuvant chemotherapy. The aim of this study was to retrospectively review the outcome of dogs with surgically excised SC MCTs undergoing adjuvant treatment or not. A secondary aim was to assess prognostic factors in the same group. Fifty-two cases were included. Recurrence rate was 15% and 63% of evaluated lymph nodes were consistent with early or overt metastasis. Median survival time (range 83–1357 days) and median time to progression (range 14–1357 days) were not reached. Factors predictive of shorter overall survival time included increasing age (HR 1.29, 95% CI 1.06–1.55, p = .0092), presence of clinical signs at presentation (HR 10.44, 95% CI 2.69–40.52, p = .0007), mitotic count >4 (HR 8.69, 95% CI 2.55–29.55, p = 0.0005), presence of multinucleation (HR 4.21, 95% CI 1.35–13.18, p = .0135), use of neoadjuvant and adjuvant chemotherapy (HR 7.16, 95% CI 1.26–40.73, p = .0266). The same factors, together with increasing tumour dimensions, were predictive for shorter progression-free survival (PFS), including increasing age (p = .0012), presence of clinical signs at presentation (p = .0045), increasing tumour dimensions (p = .0004), MC > 4 (p = .0004), presence of multinucleation (p = .0282), use of neoadjuvant and adjuvant chemotherapy (p = .0485). No variables remained significant for overall survival using multivariate analysis. There was a longer survival in cases where chemotherapy was not required (HR 0.14, 95% CI 0.03–0.68, p = .0148), and this variable remained significant for PFS on multivariate analysis (HR 0.13, 95% CI 0.02–0.76, p = .02). In conclusion, our study suggests that dogs with SC MCTs, in the absence of negative prognostic factors, may have a prolonged survival when treated with surgery alone. Further studies are needed to clarify the role of adjuvant treatment for biologically aggressive SC MCTs in dogs.