Page 637 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 28 Tumors of the Mammary Gland 615

TABLE 28.6 Summary of Published Studies Reporting Benefit from Systemic Therapy in Dogs with Malignant
Mammary Tumors
VetBooks.ir Tumor Stage Grade/Histopathology Treatment Comments and Effect Reference
Cyclophosphamide, 5-fluorouracil vs none
Evidence level 2
a
226
Stage III–IV
Any grade
Various carcinomas DFS: p < 0.01
Stage I–IV Grade 3 NSAID: firocoxib vs none Evidence level 2 160
Various carcinomas DFS: p = 0.015
Stage IV–V Grade: NA Carboplatin +/– Evidence level 2 163
NSAIDs vs none OS: p = 0.07 b
Advanced Inflammatory carcinomas NSAIDs +/– chemotherapy vs None Evidence level 3 102
Palliative intent
OS: p = 0.01
Advanced Inflammatory carcinomas NSAID (piroxicam) vs doxorubicin Evidence level 3 162
Palliative intent
PFS: p < 0.01
Stage I Grades 1, 2 Hormonal Tx Evidence level 1 p = 0.002–0.02 154
Complex and mixed Antiprogestin (aglepristone) vs none
carcinomas, PR+
Stage I–IV Grade 2 Hormonal Tx Evidence level 1 p = 0.03 79
OHE vs intact
Stage III–IV Grades 2, 3 DDAVP (desmopressin) vs none Evidence level 1 165
Various carcinomas DSF: p = 0.001
NA Extraskeletal Doxorubicin or cisplatin vs none Evidence level 3 164
Osteosarcoma, including Mixed primary sites
mammary OS: p = 0.02
a Evidence level 1: Prospective randomized trial; level 2: Prospective, nonrandomized trial; level 3: Retrospective; level 4: Case report(s); level 5: Extrapolation from human breast cancer studies.
b Significance set at p = 0.1.
NSAID, Nonsteroidal antiinflammatory drug; OST, overall survival time; PFS, progression-free survival; PR, progesterone receptor.

Mammary Tumors in Cats in the source population because no information regarding OHE
status was provided.
Epidemiology and Risk Factors
Epidemiology Risk Factors
There are fewer epidemiologic studies regarding the incidence of Three main risk factors in cats have been identified: age, breed,
mammary neoplasia in cats compared with dogs. Furthermore, and hormonal influence.
because of differences in veterinary care for cats, the available
data likely underestimate the true incidence of disease. Accord- Age
ing to data from one of the largest Swedish insurance companies, As in the dog, mammary neoplasia is a disease seen predominantly
approximately 40% to 50 % of all dogs had insurance to cover in middle-aged to older cats. The mean age of diagnosis is between
veterinary expenses, whereas only 20% of cats had such cover- 10 and 12 years of age. 1,172–175 Risk increases incrementally with
age. 168,169 Another study from the United States also reported that age but does not become significant until 7 to 9 years, according
a significantly lower percentage of cats receives regular veterinary to the age-specific incidence curves from the CANR, and contin-
1
care compared with dogs. 170 ues to increase up until 12 to 14 years.
The overall MGT incidence is lower in cats than in dogs.
According to the California Animal Neoplasia Registry (CANR), Breed
MGTs represent the third most common tumor in female cats Siamese cats are significantly younger when diagnosed with MGTs
(after skin tumors and lymphoma) with an annual incidence rate and risk plateaus at 9 years of age. 176 In general, genetic predispo-
of 25.4/100,000 and 12% of tumors in cats regardless of sex. sition for a disease is often associated with a younger age of diag-
1
Data from an animal tumor registry from two provinces in north- nosis. Siamese cats appear overrepresented compared with other
ern Italy reported that MGTs represented 16% of all tumors in breeds. 176,177 However, Siamese cats have an increased risk for
cats and 25% in female cats. 171 Data from a Swedish insurance many tumor types and not only MGTs. 178–182 It is therefore pos-
company indicate that MGTs were the most common cancer rep- sible that the increased incidence in Siamese cats is due to breed-
resenting 40% of all tumor-related claims in cats. 168 It is unclear associated germline alterations in common tumor susceptibility
whether the higher relative incidence of MGTs in the latter stud- genes or defective tumor suppressor gene function that confers
ies is due to differences in neutering practices or use of progestins increased risk for many different malignancies.