Page 1336 - Clinical Small Animal Internal Medicine

1274 Section 11 Oncologic Disease

Metronomic chemotherapy, which is intended to prevent after SBRT. SBRT may be ideal for select patients and
VetBooks.ir tumor angiogenesis, is based on more frequent and likely not of benefit for dogs lacking cardiovascular
disturbances and/or incidentally diagnosed. As the use
low‐dose drug administration lacking a rest period com­
pared with conventional chemotherapy. Metronomic
dates, and better define the survival benefit. Standard
chemotherapy lends itself to minimal toxicity and is of SBRT evolves we will recognize appropriate candi­
often cost‐effective and convenient. and metronomic chemotherapy alone or combined with
One small study evaluating canine splenic HSA com­ small molecule inhibitors may be attempted, especially if
pared the use of low‐dose chemotherapy in combination metastasis is evident.
with piroxicam versus the standard of care chemother­ In patients affected by cardiac lymphoma with clini­
apy, doxorubicin. This study found no statistical differ­ cally significant pericardial effusion, palliative pericardi­
ence in survival between the groups, leading to the ocentesis is required. Considered to be stage V, substage
conclusion that low‐dose orally administered chemo­ B, cardiac lymphoma may be treated with CHOP‐based
therapy may be an effective alternative to conventional chemotherapy protocols.
chemotherapy. A group at Washington State University Mesothelioma patients may have a palliative pericard­
used daily dosing of an alkylating agent, lomustine, ectomy performed, but clinically significant pleural
with or without nonsteroidal antiinflammatory drugs effusion typically develops, and pericardectomy has not
(NSAIDs) to evaluate the toxicity. The majority of the been shown to decrease the occurrence of clinical signs
81 dogs in this study had macroscopic tumor and/or or survival time. In patients affected with mesothelioma,
metastasis with osteosarcoma and visceral HSA most carcinomatosis or sarcomatosis (with or without malig­
prevalent. Thirty­six percent of dogs experienced stable nant effusion), short‐term benefit has been obtained
or improved disease. Although minimal, mild to moder­ with intracavitary chemotherapy. Intracavitary carbopl­
ate adverse hematologic and gastrointestinal events atin and/or mitoxantrone yielded a 333‐day median sur­
occurred and an unexpectedly higher number experi­ vival time. Three dogs with pleural mesothelioma treated
enced azotemia (13%). Currently, there are no placebo‐ with intracavitary cisplatin had complete resolution of
controlled studies available for cardiac HSA. Tyrosine their effusions for 129, 289 and over 306 days. Resolution
kinase‐mediated proliferation inhibition has been of effusion occurred within one or two treatments for all
observed in cell lines of canine HSA when exposed to three dogs.
dasitinib and imatinib alone and in conjunction with Intrapericardial lipomas may be addressed surgically if
doxorubicin. The use of tyrosine kinase inhibitor therapy clinically important right‐sided inflow obstruction of the
alone or in combination with standard or metronomic heart is documented.
chemotherapy has yet to yield improved survival times in
the treatment of cardiac HSA.
Early surgical excision is the preferred method of treat­ Prognosis
ment for heart‐based tumors. However, in the majority
of cases complete surgical excision is not possible. The prognosis for cardiac HSA is generally considered
Palliative pericardiocentesis and partial pericardiectomy to be grave. Median survival times (MST) with pallia­
are viable treatment options for patients with pericardial tive pericardiocentesis alone have been reported at
effusion secondary to HBT. A retrospective study of 6 11 days (range 0–208 days). A MST of 43 days was
dogs treated with stereotactic body radiation therapy achieved in eight dogs undergoing pericardiectomy
(SBRT) for heart­base tumors confirmed or presumed to and surgical resection of a RA HSA. In eight dogs with
be chemodectomas was performed at the North Carolina pericardiectomy and RAu masses, MST was 90 days.
State University Veterinary Hospital. Respiratory and This difference in MST may be explained by the smaller
motion management was key to the accurate delivery of size of auricular masses. In a separate report, 15 dogs
a minimum of 30 Gray (Gy) delivered in three 10 Gy frac­ with pericardiectomy and RA mass resection experi­
tions. Four tumors were assessed after SBRT; tumor vol­ enced a MST of 42 days. In eight postoperative patients,
ume decreased by 30­76%. Possible treatment­related the addition of doxorubicin‐based chemotherapy sig­
complications included cough, tachyarrhythmias, and nificantly improved MST to 175 days. In nonsurgical
congestive heart failure. Two dogs experienced sudden cases doxorubicin‐based protocols may offer MST of
death 150 and 294 days after SBRT. Three dogs were 120 days. Pericardiectomy may be performed by one
alive at the time of the report (408 and 751 days after of two techniques: surgical (thoracotomy) or thoras­
SBRT) and one dog died of unrelated disease 1,228 days copic‐assisted pericardiectomy. However, if mass
after SBRT. While this protocol offered rapid tumor removal is intended, thoracotomy would be the
reduction, cardiac arrhythmias assumed to be tumor or ideal approach based on the experience level of the
treatment related and sudden death commonly occurred surgical team.