Oncology Update – Feline Lymphoma (LSA)
Central Toronto Veterinary Referral Clinic
Kevin Finora DVM, Diplomate ACVIM (Oncology and Small Animal Internal Medicine)
Feline Lymphoma (LSA)
Feline LSA is the second most common feline cancer. It is one of the most treatable cancers, having excellent responses to therapy with variable survival times. I have outlined below important information and details about this feline cancer.
- The average age of onset is 11 years.
- FeLV infection is a known risk factor for the development of LSA. LSA may develop years after infection, even if the virus was cleared. This delay is due to the insertion of an oncogene into the genome which can remain dormant for years before being “turned on.”
- Most older cats with LSA are FeLV negative which most younger cats are positive.
- FeLV infection is associated with mediastinal LSA (Siamese and Oriental breeds at highest risk).
- Chronic inflammation appears to be a risk factor for the development of LSA. IBD can malignantly transforming into GI LSA.
- Well controlled IBD results in less inflammation and thus a lower risk of transforming to LSA.
- The most common site for GI LSA is the small intestine followed by stomach and ileocecocolic junction.
- Full thickness GI biopsy is needed for diagnosis. Surgery is recommended. Endoscopic biopsies are of less reliable diagnostic value.
- Cytology of mesenteric lymph nodes has no diagnostic value, as IBD can cause identical cytological changes, again biopsy is required.
- Peripheral lymphadenopathy is rare in cats and other causes of lymphadenopathy (ie. lymph node hyperplasia syndrome) should be considered more likely than LSA.
- In cats, LSA is described by location, location is prognostic
- Mediastinal: usually FeLV (+)ve. Survival with chemotherapy: 2-3 months.
- Renal: 25% FeLV (+)ve. 50% will spread to CNS. Survival with chemotherapy: 3-6 months.
- GI: Survival with chemotherapy: 7-10 months.
- Nasal: Survival with chemotherapy, radiation or chemotherapy and radiation: 1-1.5 years.
- Small Cell GI: with chronic low grade chemotherapy, survival can reach to years.
- Hodgkin’s-Like LSA: This emerging form of head and neck LSA in cats can potentially be cured with surgery and chemotherapy.
- Gastric LSA: With chemotherapy excellent results, long term survival is possible, even cure.
- Multi-agent chemotherapy protocols, with doxorubicin, offer the highest response rates and survival times.
- Response rates with treatment vary between 50-70%.
- Substitution of drugs which cross the blood brain barrier into the treatment protocol appears to decrease the metastatic rate of renal LSA to the CNS.
- A good response to therapy is a major positive prognostic indicator.
- Cats very rarely develop any side effects associated with chemotherapy.
Dr. Kevin Finora is a Board Certified Oncologist and Small Animal Internist who is part of the Healthcare Team at the Central Toronto Veterinary Referral Clinic. He is available for referrals and consultations Monday to Thursday (including Monday and Tuesday evenings). Please contact him with any oncology questions or concerns.
Posted by: Michael Goldstein, DVM, Diplomate ACVIM
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