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612 Lymphoma Rescue Therapy

Lymphoma Rescue Therapy Client Education
Sheets
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BASIC INFORMATION
cytotoxins and other harmful chemicals from
be needed for some patients.
cells. P-glycoprotein overexpression is a major receptor rearrangement (PARR) analysis may
Definition contributor to the multidrug resistance • Bone marrow aspiration for cytologic analysis
Rescue therapy attempts to induce remission (MDR) phenotype, causing simultaneous (p. 1068): to clarify cause of cytopenias
in a patient with lymphoma that has failed resistance to vinca alkaloids, doxorubicin,
first-line treatment or establish remission prednisone, and other drugs. TREATMENT
in a patient that has relapsed after previous • Relapse of lymphoma can also result from
treatment. Relapse is the return of signs of controllable factors, including inadequate Treatment Overview
disease in a patient that previously attained dosing (e.g., empirical dose reductions • The goal of rescue treatment for lymphoma
and maintained clinical remission (CR) for at to reduce potential or actual side effects), is to reduce disease burden below that which
least 30 days after completion of treatment. inadequate treatment intervals (e.g., owners causes clinical signs, while simultaneously
electing to postpone treatments), and pre- avoiding adverse effects.
Synonyms treatment with corticosteroids (controversial). • Consultation with a veterinary oncologist
Reinduction therapy is strongly recommended for treatment of
relapsed disease.
Epidemiology DIAGNOSIS • If the relapse interval is > 2 months after
SPECIES, AGE, SEX Diagnostic Overview cessation of treatment, remission reinduction
Dogs and cats, any age, either sex Relapse is suspected in a patient with lymphoma is attempted using the induction protocol
that has recurrence of node enlargement or that was initially successful.
RISK FACTORS organomegaly during a course of chemotherapy • If the relapse interval is < 2 months after the
• Previous diagnosis of lymphoma (by or after completion of a chemotherapy protocol. cessation of treatment, reinduction using the
definition) Patients typically have recurrent signs of illness initial protocol can be attempted, but rescue
• Immunophenotype (e.g., T cell) similar to those at diagnosis of lymphoma. protocols may be more effective options in
• Anatomic location (e.g., gastrointestinal [GI], Relapse can be confirmed similar to diagnosis many cases.
cutaneous) (e.g., using fine-needle aspirates of enlarged • If reinduction chemotherapy does not achieve
• Poor treatment protocol compliance lymph nodes). remission and the patient is resistant to
• Pretreatment with corticosteroids (contro- first-line therapy: typically, single-drug or
versial) Differential Diagnosis combination protocols that use drugs not
Nonspecific signs (lethargy, inappetence) may employed in previous or standard protocols
Clinical Presentation occur with disease relapse or with adverse effects (e.g., CHOP: cyclophosphamide, hydroxy-
HISTORY, CHIEF COMPLAINT of recently administered chemotherapy. Infec- daunorubicin [doxorubicin], Oncovin
• Relapse of lymphoma is usually determined tious disease, potentially related to therapeutic [vincristine], and prednisone).
by recognizing disease in the same organs(s) immunosuppression, can cause similar signs. • Although achieving CR is ideal, in the
and/or tissue(s) where it was initially detected. Exam findings can help clarify the difference in rescue protocol setting, maintenance of a
• Systemic signs (lethargy, inappetence, weak- some patients, whereas advanced testing (e.g., strong partial remission (PR) can also be
ness, polyuria/polydipsia) imaging) is needed in other patients to identify a successful plan, as long as clinical signs
• Palpable mass (enlarged lymph node[s]; less occult lymphoma. resolve. Selecting a protocol that minimizes
commonly, primary neoplasm) toxicosis while maximizing the chance of
Initial Database response is ideal.
PHYSICAL EXAM FINDINGS • A minimal database, including CBC, serum • Many factors influence the choice and
• Can include, but is not limited to, generalized biochemical panel, and urinalysis, can help sequence of rescue protocols, including pet
lymphadenopathy, organomegaly, uveitis, rule out alternative diagnosis (e.g., infection), owner factors (e.g., cost, time commitment,
pallor, and fever (pp. 607 and 609) recognize changes related to lymphoma (e.g., concern about side effects), and clinician
• Regular monitoring of disease status hypercalcemia), and help select an optimal factors (e.g., limited access or experience with
after treatment, including measuring and rescue protocol. drugs, lack of experience with potential side
recording lymph node size, can allow early • Fine-needle aspiration and cytologic analysis effects, facilities).
detection of relapse (NOTE: other tests of abnormal tissue (e.g., enlarged lymph • Rescue protocols may be inappropriate for
performed at monitoring exams, such as nodes, spleen) can often provide a definitive animals with relapsed lymphoma that are
bloodwork and possibly imaging studies, diagnosis of relapse. ill from their disease (e.g., not eating and
are often appropriate). • Imaging studies, as guided by history (e.g., drinking on their own) because the chance
thoracic radiographs if respiratory signs of causing further adverse effects would likely
Etiology and Pathophysiology present), physical exam (e.g., abdominal exceed any potential benefit.
• The main cause of lymphoma relapse is radiographs if splenomegaly present), or
resistance to chemotherapy, which can be results of minimal database (e.g., abdominal Acute General Treatment
caused by pharmacokinetic factors (e.g., ultrasound if liver enzymes increased) Although the mainstay of treatment for relapsed
inability to achieve adequate drug concentra- lymphoma is chemotherapy, supportive care
tions in certain anatomic regions), inherent Advanced or Confirmatory Testing may be necessary for overtly ill patients before
factors (e.g., measurable tumors are likely to Diagnostic testing is guided by the specific starting treatment (pp. 602 and 603).
contain 10-1000 inherently resistant cells), clinical signs that are noted when relapse is
and acquired drug resistance (e.g., reduced confirmed. Chronic Treatment
drug uptake and/or accumulation). • Serial exams (e.g., every few weeks), analysis Consultation with or referral to a vet-
• P-glycoprotein (P-gp/gp-170) is an example of of lymph nodes by flow cytometry, or erinary oncologist is recommended because of
an ATP-dependent efflux pump that extrudes polymerase chain reaction (PCR) for antigen the complex nature of disease relapse. Special

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