Continuous low-dose oral chemotherapy for adjuvant therapy of splenic hemangiosarcoma in dogs.
BACKGROUND
Hemangiosarcoma (HSA) is a highly metastatic and often rapidly fatal tumor in dogs. At present, conventional adjuvant chemotherapy provides only a modest survival benefit for treated dogs. Continuous oral administration of low-dose chemotherapy (LDC) has been suggested as an alternative to conventional chemotherapy protocols. Therefore, we evaluated the safety and effectiveness of LDC using a combination of cyclophosphamide, etoposide, and piroxicam as adjuvant therapy for dogs with stage II HSA.


OBJECTIVE
We hypothesized that oral adjuvant therapy with LDC could be safely administered to dogs with HSA and that survival times would be comparable to those attained with conventional doxorubicin (DOX) chemotherapy.


METHODS
Nine dogs with stage II splenic HSA were enrolled in the LDC study. Treatment outcomes were also evaluated retrospectively for 24 dogs with stage II splenic HSA treated with DOX chemotherapy.


METHODS
Nine dogs with stage II splenic HSA were treated with LDC over a 6-month period. Adverse effects and treatment outcomes were determined. The pharmacokinetics of orally administered etoposide were determined in 3 dogs. Overall survival times and disease-free intervals were compared between the 9 LDC-treated dogs and 24 DOX-treated dogs.


RESULTS
Dogs treated with LDC did not develop severe adverse effects, and long-term treatment over 6 months was well-tolerated. Oral administration of etoposide resulted in detectable plasma concentrations that peaked between 30 and 60 minutes after dosing. Both the median overall survival time and the median disease-free interval in dogs treated with LDC were 178 days. By comparison, the overall survival time and disease-free interval in dogs treated with DOX were 133 and 126 days, respectively.


CONCLUSIONS
Continuous orally administered LDC may be an effective alternative to conventional high-dose chemotherapy for adjuvant therapy of dogs with HSA.
Lana
Susan
S
Animal Cancer Center, Department of Clinical Sciences , Colorado State University, Ft. Collins, 80523, USA.
U'ren
Lance
L
Plaza
Susan
S
Elmslie
Robyn
R
Gustafson
Daniel
D
Morley
Paul
P
Dow
Steven
S
D000284:Administration, Oral; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use; D004283:Dog Diseases / Q000188:drug therapy*; D004285:Dogs; D004317:Doxorubicin / Q000008:administration & dosage / Q000627:therapeutic use*; D005047:Etoposide / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000627:therapeutic use*; D005260:Female; D006394:Hemangiosarcoma / Q000188:drug therapy / Q000662:veterinary*; D008297:Male; D013160:Splenic Neoplasms / Q000188:drug therapy / Q000662:veterinary*
D000970:Antineoplastic Agents; D005047:Etoposide; D004317:Doxorubicin