Objective—To examine the effect of adjuvant doxorubicin
chemotherapy on outcome in dogs with highgrade
(grade 3) soft tissue sarcomas (HGSTSs).
Design—Retrospective case series.
Procedures—Medical records of dogs with HGSTSs
were reviewed. Dogs treated with surgery alone or
receiving single-agent doxorubicin chemotherapy
postoperatively were included in the study. Owners
and referring veterinarians were contacted for followup
information. Slides from histologic sections were
reviewed to confirm the diagnosis of HGSTSs. Cases
in which follow-up examination was not performed
and radiation therapy or chemotherapy other than
doxorubicin was administered were excluded.
Results—39 dogs met inclusion criteria. Twenty-one
dogs received adjuvant doxorubicin. Tumor-, patient-,
and treatment-related variables were not significantly
associated with measured outcomes including local,
metastatic, and overall disease-free intervals as well
as survival time. Overall median disease-free interval
was 724 days with a median survival time of 856 days
for all dogs.
Conclusions and Clinical Relevance—Adjuvant doxorubicin-based chemotherapy did not benefit this population of dogs with HGSTSs. Outcome for visceral HGSTSs
was similar to that of nonvisceral HGSTSs in these cases.
(J Am Vet Med Assoc 2005;227:1442–1448)
Objective—To determine the effect of dietary n-3 fatty acids on the pharmacokinetics of doxorubicin in dogs with lymphoma.
Animals—23 dogs with lymphoma in stages IIIa, IVa, and Va.
Procedure—Dogs receiving doxorubicin chemotherapy were randomly allocated to receive food with a high (test group) or low (control group) content of n-3 fatty acids. Serum doxorubicin and doxorubicinol concentrations were measured via high-performance liquid chromatography before and 6 to 9 weeks after initiation of the diets. Lymph node concentrations of doxorubicin were assessed 6 hours after the initial treatment. Dogs' body composition was assessed by means of dual-energy x-ray absorptiometry scans.
Results—No significant differences in doxorubicin pharmacokinetics were detected between treatment groups. Significant differences existed between the first and second sampling times among all dogs for area under the curve, maximum serum concentration, and clearance. Differences in body composition did not affect measured pharmacokinetic variables. The terminal elimination half-life was longer in dogs in which a long-term remission was achieved than in dogs that did not have remission.
Conclusions and Clinical Relevance—Dietary supplementation of n-3 fatty acids is common in veterinary patients with neoplasia, but supplementation did not affect doxorubicin pharmacokinetics in this population of dogs. Explanations for the beneficial effects of n-3 fatty acids other than alterations in the pharmacokinetics of chemotherapy drugs should be investigated. Dogs may metabolize drugs differently prior to remission of lymphoma than when in remission. The pharmacokinetics of doxorubicin at the time of the first administration may predict response to treatment.
Objective—To evaluate factors associated with second remission in dogs with lymphoma retreated with a cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) protocol after relapse following initial treatment with a first-line 6-month CHOP protocol.
Design—Retrospective case series.
Animals—95 dogs with lymphoma.
Procedures—Medical records were reviewed. Remission duration was estimated by use of the Kaplan-Meier method. Factors potentially associated with prognosis were examined.
Results—Median remission duration after the first-line CHOP protocol was 289 days (range, 150 to 1,457 days). Overall, 78% (95% confidence interval [CI], 69% to 86%) of dogs achieved a complete remission following retreatment, with a median second remission duration of 159 days (95% CI, 126 to 212 days). Duration of time off chemotherapy was associated with likelihood of response to retreatment; median time off chemotherapy was 140 days for dogs that achieved a complete remission after retreatment and 84 days for dogs that failed to respond to retreatment. Second remission duration was associated with remission duration after initial chemotherapy; median second remission duration for dogs with initial remission duration ≥ 289 days was 214 days (95% CI, 168 to 491 days), compared with 98 days (95% CI, 70 to 144 days) for dogs with initial remission duration < 289 days.
Conclusions and Clinical Relevance—Findings suggested that retreatment with the CHOP protocol can be effective in dogs with lymphoma that successfully complete an initial 6-month CHOP protocol.