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The Oncology Committee works to advance oncology knowledge and care through education and through raising awareness of effective and accessible treatments for pets with cancer.
With cancer increasingly common in pets, the Oncology Committee was created to raise awareness of the latest thinking in cancer therapy, promote best practice globally and overcome global variations in oncology treatment. Since its inception, the committee has created a range of resources, including an ‘oncology glossary,’ which has been translated into multiple languages and a set of ‘Cancer Fast Facts’ for the veterinary team and for pet owners. The Oncology Committee has also created three virtual oncology journal issues with the Journal of Small Animal Practice, the open access Journal of Feline Medicine and Surgery, and the Journal of the American Veterinary Medical Association.
The WSAVA Oncology Working Group (WOW) gratefully acknowledges the support of the Journal of Feline Medicine and Surgery in making this collection of feline oncology articles freely available on the WSAVA website to further WOW’s mission to help overcome the asymmetric degrees of regional veterinary oncology development, resource limitations (both financial and human), and active communication (based on both language and cultural nuances).
The articles in this collection were selected from those published in the Journal of Feline Medicine and Surgery over the past 10 years via a PubMed search for “cancer AND Journal of Feline Medicine and Surgery”. This identified 155 articles. Because WOW is a global community, the articles chosen for this collection focused on widely available cancer therapies, tumors important to feline oncology worldwide and some of the most important review articles published in the Journal of Feline Medicine and Surgery.
December 2022: Feline injection-site sarcoma: ABCD guidelines on prevention and management.
The 2015 feline injection site sarcoma (FISS) ABCD guidelines are a must-read for any veterinary practitioner. It is a concise and to-the-point review article of one of the most difficult to manage feline tumors. FISSs are rare tumors that occur after vaccination or injection and have characteristics of fibrosarcoma, but with a more malignant behavior. They are locally very aggressive and demand radical excision to prevent recurrence. Metastases occur in 10–30% of cases. Cancer therapy may improve prognosis, but the key is prevention. Cats should be vaccinated as often as necessary but as infrequently as possible. Injections should only be given in locations that allow easy excision, and after vaccination the site needs to be closely monitored for tumor development..
Dr Jolle Kirpensteijn – WSAVA Oncology Working Group Member – Netherlands and USA
November 2022: Feline alimentary lymphoma: 2. Further diagnostics, therapy and prognosis
This two-part review of the common cancer, feline alimentary lymphoma, is a useful tool for general practitioners and feline clinicians to understand, diagnose and treat the different presentations of gastrointestinal lymphoma in cats.
Part 2 covers the invasive diagnostic tests, with examples of cytology, histology and immunohistochemistry used for diagnosis. The pros and cons of laparoscopic versus open surgery versus endoscopy are discussed and summarized in a table to help clinicians make the best recommendation possible for their patients and communicate that information to owners. Examples of common chemotherapy protocols are included in tabular form. Early data on radiation therapy for alimentary lymphoma is included in this review.
This publication is 10 years old and does not contain information on clonality testing (PARR), but is still a useful read for veterinarians looking for a good summary of feline alimentary lymphoma.
Dr Pachi Clemente-Vicario Member, WSAVA Oncology Working Group – Spain
October 2022: Feline alimentary lymphoma: 1. Classification, risk factors, clinical signs and non-invasive diagnostics.
This two-part review of the common feline cancer, alimentary lymphoma, is a useful tool for general practitioners and feline clinicians to understand, diagnose and treat the different presentations of gastrointestinal lymphoma in cats.
Divided in two parts, Part 1 covers general information about the three types of alimentary lymphoma in cats (low grade, high grade and large granular lymphocyte lymphoma), risk factors, differential diagnosis and non-invasive diagnostic tests. The review is nicely Illustrated with tables and figures that highlight the key factors. Table 1 summarizes the most relevant information for diagnosis, prognosis and treatment. The text covers in detail the risk factors and the findings on bloodwork and abdominal ultrasound, with examples of clinical cases.
Written 10 years ago, it does not include the most recent information about clonality tests (PARR) but still it may be considered current in terms of general approach to diagnose the different types of alimentary lymphoma, either for a quick read of key points or for more detailed reading with extended information.
Dr Pachi Clemente-Vicario Member, WSAVA Oncology Working Group – Spain
September 2022: Cats and chemotherapy: treat as ‘small dogs’ at your peril.
Veterinarians must always keep in mind that cats are never small dogs, especially when it comes to treating cancer, impacting chemotherapy drug dosing. This article does just that by describing important considerations of chemotherapy administration in cats. Metabolic differences between dogs and cats, and even male and female cats, can affect drug metabolism rates (causing rapid drug elimination) and need to be assessed to ensure safe drug administration. When administering multiple cytostatic drugs, or treating cats with kidney or liver disease, drug doses may need to be reduced.
The most common side effect and the dose-limiting toxicity for most chemotherapy drugs in cats is neutropenia. Other side effects for most commonly used drugs in cats are also described. Targeted therapies (masitinib, toceranib and imatinib) can produce toxicity and cats need to be monitored as carefully as if they were receiving traditional chemotherapy drugs.
Chemotherapy drug dosing in cats has challenges since not all drugs are dosed based on body surface area and body surface calculation may not be accurate in cats. Tablets produced for dogs may not be right for smaller cats. The very useful tables in this article summarize current cytostatic drug dosages commonly used for cats.
Dr Natalia Ignatenko, Member, WSAVA Oncology Working Group – Ukraine
August 2022: Cats with cancer: where to start.
For any veterinarian treating feline patients, this essential review provides an overview of the approach to the feline cancer patient. Most common tumors in cats are lymphoma, squamous cell carcinoma, mammary carcinoma and soft tissue sarcoma. Veterinarians must determine if the feline patient has a mass or signs secondary to a mass or signs due to metastatic disease. Key to appropriately managing cancer patients is identifying the tumor, making an accurate diagnosis, and performing clinical staging. Sampling of masses and effusions via cytology or histology is required for diagnosis. This article summarizes advantages and disadvantages of various tumour sampling methods. Clinical staging directs treatment recommendations. For squamous cell carcinomas and soft tissue sarcomas early treatment holds the only chance of cure.
This article discusses appropriate biopsy placement to avoid jeopardizing future treatment, particularly for soft tissue sarcomas. Chemotherapy is required to treat widely disseminated but chemo-responsive disease (eg, lymphoma) or where there is a high risk of development of metastatic disease and micrometastases are likely to be present (eg, mammary carcinoma). Cancer treatment for feline patients is rapidly evolving but radiotherapy availability is still limited.
Dr Natalia Ignatenko, Member, WSAVA Oncology Working Group – Ukraine
July 2022: Metastatic feline mammary cancer: prognostic factors, outcome and comparison of different treatment modalities – a retrospective multicentre study.
Feline mammary carcinoma (FMC) is one of the leading causes of cancer-related deaths in middle-aged and older cats, attributed to the high metastatic rate.
Which cats with FMC have a poor prognosis?
If metastases are present, the tumor specific survival is 4 days. However, in this study, overall survival ranged from 0 to 554 days, which supports that survival is impacted by more than the presence of metastasis. This paper focused on specific critical factors: the presence of signs at diagnosis and pleural effusion appears to be important negative prognostic factors. Finally, regarding treatment options, no significant differences in progression and survival were found between the three treatment groups: 1. maximum tolerated chemotherapy; 2. metronomic chemotherapy; 3. Toceranib phosphate. Group 1 had higher numbers of adverse events. The authors suggest tumor resection may play a role in prolonged survival.
June 2022: Mammary tumours in the cat: size matters, so early intervention saves lives
This article is a review focused on an overview of feline mammary tumors from etiology to treatment. The entire manuscript is written in a very clear, systematic and understandable way, making it easy to read and thus apply the information to the management of feline patients.
This article is a must-read for anyone wishing to learn or update their knowledge on feline mammary tumors.
May 2022: Musculoskeletal neoplasia: an important differential for lumps or lameness in the cat.
This 2012 article focuses on feline musculoskeletal tumors and highlights 2 specific tumors:
For FISS, we refer the reader to the2015 FISS ABCD guidelinesfor important information on managing FISS. Feline osteosarcoma (OSA) is a rare primary bone tumor in cats that shows a locally aggressive behavior but seldom metastasizes. This biological behavior is very different from that of canine OSA. In cats, radical tumor excision, such as amputation, often leads to long term median survival time of 24-44 months; in dogs, radial excision rarely results in long term survival. There is a significant difference in location, with axial OSA carrying a shorter survival time than appendicular OSA.
In concluding, the authors describe a peculiar syndrome in cats of digital metastasis of pulmonary tumors or lung-digit syndrome, of unknown etiology.
April 2022: Retrospective evaluation of toceranib phosphate (Palladia) use in cats with mast cell neoplasia
Toceranib was administered orally to cats with mast cell tumors at a median dose of 2.5 mg/kg three times per week.
Was it useful in cats with mast cell neoplasia?
Yes. Clinical benefit (a combination of complete (CR) and partial responses (PR) and stable disease (SD)) was observed in 80% (40/50) cats, including 86% (19/22) cats with cutaneous (seven CR, 10 PR, two SD), 80% (8/10) with visceral (three CR, four PR, one SD) and 76% (13/17) cats with gastrointestinal (three CR, eight PR, two SD) involvement.
What were the risks for this medication?
Thirty studied cats (60%) experienced a total of 82 adverse events (AE); however, the majority of AEs (71/82; 87%) were low-grade. In rare instances increases in alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities were noted.
How does this help the practicing veterinarian?
Toceranib is a good choice for feline MCT when a chemotherapy agent is required. Response rate is high and adverse events minimal. The role of glucocorticoids in treatment of these cats was not evaluated.
Dr Martin Soberano, Chair, WSAVA Oncology Working Group – Mexico, Argentina, Chile
March 2022: Mast cell tumors in cats: clinical update and possible new treatment avenues.
This review contains everything a practicing veterinarian needs to know about feline mast cell tumours (MCT). While MCT are less common in cats than in dogs, MCT are the most common tumour of the spleen, and second and third most common cancer of the skin and the intestine, respectively.
Diagnosis can be achieved by cytology or with histopathology. Histological grading is not considered prognostic in cat, but the mitotic index has some prognostic value. Tumor staging (blood work with coagulation profile, abdominal ultrasound and thoracic radiography) should always be performed in case of feline MCT with aggressive clinical behaviour, multiple cutaneous nodules or palpable abdominal masses.
Treatment of MCT depends on the location and stage. Most solitary cutaneous MCTs are benign, and excision (even with incomplete margins) is often curative. Splenectomy is considered the treatment of choice for splenic MCT and long-term survival can be achieved even when skin metastases are already present. Intestinal MCT carries a poor prognosis, but surgery and chemotherapy can potentially increase survival. Systemic treatment is reserved for advanced stage/metastatic/ cutaneous MCTs not amenable to surgical excision. The most common and effective drugs used in cats are lomustine and toceranib, but vinblastine, cyclophosphamide and chlorambucil have also been occasionally used with success.
Dr Antonio Guiliano, Member, WSAVA Oncology Working Group – Hong Kong .
Feb 2022: Feline injection-site sarcoma: ABCD guidelines on prevention and management.
The 2015 feline injection site sarcoma (FISS) ABCD guidelines are a must-read for any veterinary practitioner. It is a concise and to-the-point review article of one of the most difficult to manage feline tumors. FISSs are rare tumors that occur after vaccination or injection and have characteristics of fibrosarcoma, but with a more malignant behavior.
They are locally very aggressive and demand radical excision to prevent recurrence. Metastases occur in 10–30% of cases. Cancer therapy may improve prognosis, but the key is prevention. Cats should be vaccinated as often as necessary but as infrequently as possible. Injections should only be given in locations that allow easy excision, and after vaccination the site needs to be closely monitored for tumor development.
Dr Martin Soberano
Dr Jolle Kirpensteijn treasurer
Dr Natalia Ignatenko
Dr Antonio Giuliano Communications Officer
Dr Nick Bacon
Dr Pachi Clemente-Vicario
Dr Felisbina Queiroga, Executive Board Liaison
Agnieszka Dolnicka Student Ambassador
We are only able to respond to inquiries form veterinary professionals. We encourage pet owners to contact a local veterinarian.
