Page 724 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

702 PART IV Specific Malignancies in the Small Animal Patient

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• Fig. 33.10 (A) FLT-PET/CT image of a 3-year-old MN Hound cross illustrating FLT uptake in the periph-
eral nodes, bone marrow, kidneys bladder and spleen. (B) FLT-PET/CT image of the same dog 3 weeks
after his final dose of chemotherapy. The lymph nodes were small on CT with minimal FLT uptake on PET
images. Note the persistent uptake in the bone marrow, kidneys, and bladder. (Reprinted with permission
from Lawrence J, Vanderhoek M, Barbee D, et al Use of 3-deoxy-3-[ F]fluorothymidine PET/CT for evalu-
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ating response to cytotoxic chemotherapy in dogs with non-Hodgkin’s lymphoma. Vet Radiol Ultrasound.
2009;50:660–668.)
clinical signs attributable to abdominal disease, if complete stag- physiologic status of the patient, financial and time commitment
ing is necessary (e.g., for clinical trial inclusion), or if peripheral of the clients, and their level of comfort with respect to likelihood
lymphadenopathy is not part of the presentation, further imaging of treatment-related success and/or side effects. Without treat-
of the abdomen is warranted. Abdominal ultrasonography can be ment, most dogs with intermediate- or high-grade lymphoma will
important for obtaining ultrasound-guided intraabdominal samples die of their disease within 4 to 6 weeks of diagnosis, although
for diagnosis if more peripheral lesions are not evident (e.g., GI, significant variability exists. 147 With few exceptions, canine lym-
abdominal nodal, and hepatosplenic lymphoma) or if complete phoma is considered a systemic disease and therefore requires
clinical staging is required. 152 Ultrasonographic (including Doppler systemic therapy to achieve remission and prolong survival. The
ultrasound) assessment of peripheral LNs has also been explored 153 ; majority of canine multicentric lymphomas are intermediate- to
however, its clinical applicability is questionable because cytologic high-grade, and, currently, histologic and immunophenotypic
assessment of peripheral nodes is easy, inexpensive, and of higher characterization does not play a significant role in determining the
diagnostic utility. initial treatment protocol unless a diagnosis of indolent or low-
Advanced imaging modalities, including computed tomogra- grade lymphoma is confirmed. It is hoped that in the near future,
phy (CT), magnetic resonance imaging (MRI), positron emission as more clinically correlative information on the significance of
tomography (PET), or PET/CT and PET/MR imaging, are becom- the various subclassifications of lymphoma in dogs is acquired,
ing more commonplace in veterinary practice and their utility is more tailored therapeutic approaches may become available.
only now being determined. 221–226 PET/CT imaging is the current Systemic multiagent chemotherapy continues to be the therapy
standard of care for following and predicting durability of treatment of choice for canine intermediate- and high-grade lymphoma. In
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response in human patients with lymphoma, and both [ F]fluo- general, combination chemotherapy protocols are superior in effi-
rothymidine ( FLT) PET/CT and [ F]fluoro-d-glucose ( FDG) cacy to single-agent protocols. In rare cases in which lymphoma
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PET imaging have been reported in dogs with lymphoma. 224–226 is limited to one site (especially an extranodal site), the animal
18 FLT-PET/CT functional and anatomic imaging shows promise can be treated with a local modality such as surgery or radiation
for the evaluation of response to cytotoxic chemotherapy in dogs therapy (RT) as long as the client and clinician are committed to
with lymphoma and for predicting relapse before standard clinical diligent reevaluation (active surveillance) to document subsequent
and clinicopathologic confirmation (Fig. 33.10). progression to systemic involvement, should it occur.
Multidrug Combination Protocols
Treatment of Multicentric Lymphoma
Many chemotherapeutic protocols for dogs with lymphoma have
The therapeutic approach to a particular patient with lymphoma been developed over the past 30 years (Table 33.4). 116,227–251 Sig-
is determined by the subtype, stage, and substage of disease, nificant limitations arise when comparing efficacy studies in the
the presence or absence of paraneoplastic disease, the overall veterinary literature for the various published protocols. Few of