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610 Lymphoma, Multicentric (Dog)

Differential Diagnosis rapid evolution of protocols warrant consulta- chemotherapy, consisting of chlorambucil
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• Reactive lymphadenopathy tion with/referral to an oncologist. 6-8 mg/m PO q 48h as long as clinical
VetBooks.ir ○ Sepsis Acute General Treatment m PO q 24-48h for 4-6 months or as
response is seen and prednisone 20-40 mg/
○ Infectious diseases (e.g., ehrlichiosis,
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bartonellosis, systemic mycotic infection)
long as clinical response is seen, may be
• Reports on single-agent chemotherapy,
○ Pyoderma causing lymphadenopathy
cyclophosphamide, doxorubicin, and rabacfo-
• Other neoplasms (e.g., leukemia, dissemi- including prednisone, L-asparaginase, more appropriate than intensive, injectable
chemotherapy for this group of dogs.
nated histiocytic sarcoma) sadine, describe response rates of 20%-80%, • When a patient relapses and no longer
with remissions of 1-6 months. Although responds to front-line chemotherapy, rescue
Initial Database prednisone may be used as a single agent, its chemotherapy can be considered. CR rates
• CBC: to identify anemia, thrombocytopenia use before initiation of other chemotherapy for relapsed lymphoma are generally lower,
(due to lymphoblast infiltration in marrow or should be avoided because this practice may ranging from approximately 30%-50%, with
immune-mediated destruction), neutropenia, decrease response to other agents. remission durations of approximately 2-4
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or circulating lymphoblasts (i.e., leukemia) ○ Prednisone 30-40 mg/m PO q 24h for months (p. 612).
• Serum biochemistry panel: to identify 2-4 weeks, then continued at 20-40 mg/
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paraneoplastic hypercalcemia or identify m q 24-48h as long as clinical response Nutrition/Diet
liver or renal value abnormalities that suggest is seen Dogs with lymphoma have alterations in
organ involvement and may alter ability to ○ Doxorubicin 50%-75% CR rate for 4-6 carbohydrate, protein, and lipid metabolism
metabolize chemotherapeutic agents months and may benefit from a low-carbohydrate/
• Urinalysis ± urine culture and sensitivity: to • Reports on dual-agent chemotherapy involv- moderate-quantity, high-quality protein diet.
identify urinary tract infections secondary ing alternating rabacfosadine/doxorubicin Supplementation with polyunsaturated fatty
to immunocompromise; to identify isos- report overall response rate of 85% with acids may also be of benefit.
thenuria that, if associated with azotemia, remission of 6 months.
suggests kidney disease (e.g., hypercalcemia- • Improved remission rates and duration are Possible Complications
induced) achieved with combination chemotherapy. • Systemic chemotherapy targets rapidly
• Lymph node (or affected organ) aspiration Numerous protocols are reported with dividing cells. Due to their rapid and often
and cytologic exam: may provide a definitive variations in scheduling, drug dosages, and abnormal division and defective repair
diagnosis of lymphoma dose intensity, with most treatment protocols mechanisms, tumor cells can be destroyed
being of 6-12 months’ duration. The most by chemotherapy.
Advanced or Confirmatory Testing commonly used agents in these protocols • Some normal tissues have a high rate of
• If lymphoma is identified cytologically, the include prednisone, L-asparaginase (some cell turnover (gastrointestinal mucosa, bone
following tests are indicated as routine staging studies suggest that although very effective marrow, hair) and may be sensitive to chemo-
before initiation of chemotherapy: for inducing remission and associated with therapy, although unlike cancer cells, normal
○ Lymph node biopsy: for definitive diag- low risk of complications, inclusion of tissues can repair chemotherapy-induced
nosis, histologic grading, and possibly L-asparaginase may not significantly impact damage. Potential side effects of chemo-
immunophenotyping outcome for all patients), vincristine, cyclo- therapy include gastrointestinal upset 2-4
○ Thoracic radiographs: to identify phosphamide, and doxorubicin. CR rates are days after treatment, myelosuppression 7-10
lymphadenopathy, cranial mediastinal 65%-90%, with remissions of approximately days after treatment, and hair loss in breeds
mass, pulmonary involvement 6-11 months. Options may include with continuously growing haircoats (e.g.,
○ Abdominal ultrasound exam: to identify ○ COP (p. 603): 70%-75% CR rate for poodle, Lhasa apso, Old English sheepdog,
changes consistent with hepatic or splenic median of 3-6 months, or many terrier breeds [p. 152]).
involvement, lymphadenopathy, or other ○ CHOP (p. 603): 80% CR rate for median • All chemotherapeutic agents are potentially
sites of lymphoma of 9-10 months toxic, most are mutagenic or teratogenic,
○ Bone marrow aspiration for cytologic evalu- • Several studies have suggested that discon- and at least some are proven carcinogens.
ation (p. 1068): to identify marrow involve- tinuous (i.e., 4-6 months) chemotherapy Safe handling requires the use of a vertical
ment and/or develop better understanding protocols provide remission duration com- flow hood and closed-system drug transfer
of etiology of cytopenias parable to more traditional protocols relying device.
• Phenotyping (flow cytometry, polymerase on induction followed by maintenance (i.e.,
chain reaction [PCR] for antigen receptor up to 2-3 years) chemotherapy. Recommended Monitoring
rearrangement [PARR], immunohistochem- • Chemotherapy remains standard therapy; • Regular monitoring of remission status (e.g.,
istry): to determine B-cell versus T-cell origin however, its use in combination with other longest diameter of lymph node [LD])
• If financial restrictions prohibit these tests, treatment modalities, such as radiation ○ CR: disappearance of all evidence of disease
one may elect to omit certain tests (e.g., therapy or bone marrow transplantation ○ Partial response (PR): ≥ 30% decrease in
if CBC results are unremarkable, okay to (BMT), may improve remission duration. mean sum LD of target lesions compared
omit bone marrow aspiration), provided the ○ Half-body radiation therapy (HBRT) after with baseline
client understands that sites of disease may shortened induction chemotherapy: results ○ Stable disease (SD): insufficient decrease/
be missed and stage is uncertain. vary from superior (87% CR rate for increase to qualify for PR/PD
median of 14 months) to not significantly ○ Progressive disease (PD): ≥ 20% increase
TREATMENT different (66% CR rate for median of 8 in mean sum LD compared with smallest
months) from treatment without HBRT. mean sum LD or progression of nontarget
Treatment Overview ○ BMT in dogs achieving remission with lesions
Treatment involves administration of chemo- chemotherapy may also improve outcome, • CBC (including differential) monitoring after
therapy to promote rapid complete remission with 90% successful engraftment reported administration of chemotherapy
(CR) of cancer while maintaining excellent and median disease-free intervals of 6 and
quality of life for the patient. Special drug- 9 months, for T-cell and B-cell lymphoma, PROGNOSIS & OUTCOME
handling requirements and potentially severe or respectively, after BMT.
life-threatening adverse patient effects exist with • Low-grade lymphoma: given the chronic Several prognostic factors may help predict an
many chemotherapeutics; these concerns and indolent course of low-grade lymphoma, oral individual’s response to treatment:

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