By Sarah Guy, medwireNews Reporter
Dogs that undergo curative surgery for transitional cell carcinoma (TCC) before initiating a combination of doxorubicin and piroxicam therapy have significantly longer median overall survival (OS) than their counterparts not pretreated surgically, report researchers.
Overall, the chemotherapeutic protocol results in modest OS, progression-free survival (PFS), and biologic response rates (RR), but it is well tolerated in terms of toxicity, adds the team.
The findings support surgical excision in these animals when possible, contend Cecilia Robat (University of Wisconsin-Madison, USA) and colleagues.
The study cohort included 34 dogs with a mean age of 11 years and with TCC of the bladder, prostate, or urethra that were treated between January 2004 and December 2009. A total of 16 dogs had undergone surgery before chemotherapy, with 13 having had a curative intent procedure done at a range of 4-196 days before starting doxorubicin.
Animals received an intravenous dose of doxorubicin every 3 weeks, beginning at 30 mg/m2 up to a maximum cumulative dose of 180-240 mg/m2, in addition to a 0.3 mg/kg oral dose of piroxicam each day.
In all, eight animals experienced no adverse events (AEs). Among those that did, gastrointestinal events were the most common, graded according to the Veterinary Cooperative Oncology Group - Common Terminology Criteria for Adverse Events. Five dogs received only one dose of doxorubicin, and two of these developed a grade 3 toxicity or higher, two died of complications, and one developed progressive disease and was transferred to another therapy.
Among the 23 dogs with available data, the overall treatment RR was 8.7%, with 14 dogs exhibiting stable disease, seven having progressive disease, and two having a partial response - defined as at least a 30% decrease in the longest tumor diameter on ultrasound.
The overall median PFS and OS were 103 and 168 days, respectively, write Robat et al in the Journal of Small Animal Practice. And while cytoreductive surgery did not prolong PFS, it significantly prolonged median OS, at 217 days versus 133 days for dogs that did and did not receive it, respectively.
This result may, however, "be a reflection of tumour location and volume," warn the researchers.
"Small, apical/mid bladder tumours are much more amenable to surgical excision than the more commonly recognised trigonal TCCs," they suggest, adding that prospective studies employing more accurate imaging techniques are needed.
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