Gastrointestinal Lymphoma in Cats

An Overview

Robyn Elmslie, DVM, DACVIM (Oncology)
Phyllis Glawe. DVM, MS. DACVIM (Oncology)

Quick facts at a glance

• Lymphoma is the most common feline cancer, accounting for one-third of all malignancies.
• Recent studies indicate that the gastrointestinal (also known as alimentary) form is the most common anatomical site in the cat.
• Unlike other forms of feline lymphoma, gastrointestinal lymphoma is less likely to be associated with feline leukemia virus infection (< 30% are FeLV positive.)
• Two main categories of gastrointestinal lymphoma are recognized: the diffuse (multifocal) and solitary types.
• Treatment of gastrointestinal lymphoma may require surgery (to remove a solitary mass causing obstruction) combined with chemotherapy. The diffuse form is treated with chemotherapy only.
• Surgical resection of a solitary mass does not improve overall survival times.
• The most significant prognostic factor associated with duration of remission is the presence of a complete response following chemotherapy.

What are the common clinical signs associated with GI lymphoma in cats?

Middle age to older cats tend to be more commonly affected with this disease.

Vomiting, anorexia and weight loss are the most common clinical signs.  Diarrhea, straining to defecate, blood tinged stool or vomit are less common clinical signs.  Mild clinical signs may be noted for months until severe signs necessitate examination and diagnostic evaluation.  Treatment with medications such as prednisone can alleviate clinical signs early in the course of the disease.  Although this treatment is beneficial to the patient, steroid therapy may delay the determination of a definitive diagnosis and decrease response to chemotherapy.

How is gastrointestinal lymphoma diagnosed?

A thorough physical examination is critical in the evaluation of the feline patient suspected of lymphoma.  This exam will often determine which methods are used to confirm the diagnosis.  Often, a complete blood count, platelet count, biochemistry profile, urinalysis and radiographs are performed.  Other tests that should be considered include abdominal ultrasound with fine needle aspiration for cytology or ultrasound-guided-biopsy, endoscopy with biopsy or abdominal exploratory surgery with biopsies. 

Abdominal ultrasound can evaluate the integrity of the stomach, intestines and lymph nodes and facilitate sampling of abnormal tissue.  Endoscopy is another minimally invasive procedure used to evaluate the inside lining of the stomach and proximal small intestine.  Biopsies of these mucosal linings can be performed to confirm the diagnosis. General anesthesia is required for this procedure.  Exploratory surgery not only allows for biopsy of lesions, but also for removal of tumors which may be obstructing the gastrointestinal tract.

Is supportive care required before initiating chemotherapy?

Cats that are protein-deficient, have low red cell counts due to gastrointestinal blood loss and have significant weight loss may require supportive measures prior to initiating chemotherapy.  Administration of plasma or blood, fluid therapy or placement of feeding tubes may be recommended for these patients.  In general, the more advanced the cancer at the time of diagnosis, the less likely we are able to control its devastating effects with chemotherapy.

What is the prognosis for gastrointestinal lymphoma with treatment?

Solitary gastrointestinal forms of lymphoma may carry a significantly better prognosis than the diffuse forms.  Surgical excision of solitary masses may enhance short term quality of life but chemotherapy is still required for prolonged survival times.

Gastrointestinal lymphoma in cats is more responsive to chemotherapeutic agents than other gastrointestinal tumors.  These agents are administered in either an oral or injectable form at specific prescribed times.  Such a group of treatments is called a chemotherapy protocol.  One study using a combination of 5 chemotherapy drugs reported a median first remission of 5 months in 95% of cats treated.  The overall survival of these patients was 9 months.  In general, the severity and extent of the cancer when initially diagnosed affect the duration of remission. 

The most significant prognostic factor determining survival time is the initial response to chemotherapy.  The significance of the degree of response to chemotherapy however is contradictory.  A recent study reported that there was not a significant difference in survival time among cats achieving a complete response to chemotherapy as compared to cats achieving a partial response.  Median survival time for both groups was 9 months.

How do cats respond to chemotherapy?

Most cats tolerate chemotherapy very well.  It is our experience that > 75% of pet owners are satisfied with their pet's quality of life while receiving treatment.  As lymphoma is not curable, our emphasis is placed upon this enhanced quality of life while undergoing therapy.  Acceptable side effects which may be noted in cats include loss of appetite, vomiting, diarrhea and listlessness for 1-2 days following treatment.  These effects are fortunately self-limiting.  Occasionally, chemotherapy dose reduction or anti-nausea medication may be required.

There are a few feline patients that do not tolerate oral chemotherapy agents.  In these cases, we can adjust the protocol to include only injectable medications.  A small percentage of patients do not tolerate chemotherapy treatments at all.  Persistent severe vomiting, diarrhea, low cell counts and poor quality of life necessitate discontinuation of therapy and allowing the lymphoma to follow its natural course.

Why do we treat cats with lymphoma?

Our feline pets are an integral part of our lives and our family.  The decision to pursue therapy for a malignancy in a beloved pet is a difficult one.  The emotional concerns,  financial obligations and time invested are important factors to consider.  Our objective is to extend the pet's life with good quality time.  Both the pet and all members of the family should enjoy this extra time.

What is the cost of treatment?

We will review the costs of all diagnostic tests indicated to determine the type and extent of the cancer.  All options for treatment will be discussed, as well as the costs associated with them.  Please do not hesitate to ask questions and review our discussions when you feel the need to do so.

Is this contagious to other cats?

Lymphoma is not contagious to other cats or humans.  However, if the patient is FeLV positive, other cats in the household should be tested for this viral infection.