Page 635 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 28 Tumors of the Mammary Gland 613

assessment is critical for malignant MGTs, and additional sur- physical examination, yet all three had residual neoplastic cells at
gery should be pursued if incompletely excised. In one retrospec- the surgical margins. 102 Interestingly, two of the dogs also received
adjuvant chemotherapy and were among the longest survivors in
tive study, the MST was 15.5 months for dogs with incomplete
VetBooks.ir histologic excision of their MGT versus 22.8 months for dogs that study. 102 Radiation therapy can be considered for palliation
of dogs having clinical signs associated with presence of an inflam-
with complete histologic excision, and 70 days versus 872 days,
respectively, in another retrospective study. 150,75 Elective unilat- matory carcinoma. 151
eral or bilateral chain mastectomies may be reasonable for young
intact bitches with multiple MGTs because there is the possibil- Systemic Treatment
ity of development of additional tumors (Fig. 28.4). 123 Few clinical studies have investigated systemic therapy for
Surgical excision is questionable as a treatment for dogs pre- MGTs, and efficacy has not been evaluated and confirmed
senting with inflammatory carcinoma because of the profound according to the highest evidence-based standards. Despite
diffuse microscopic extent of cutaneous disease, the significant this uncertainty, chemotherapy is routinely recommended and
metastatic rate, and the local tissue coagulopathy that may be administered in dogs with “high-risk” tumors. This practice is
present. In 43 dogs with inflammatory carcinoma, only three dogs based on the recognition that dogs with large tumors, posi-
were considered suitable for unilateral chain mastectomy based on tive LNs, and aggressive histology are not treated effectively

A B

C D

E
• Fig. 28.4 (A) Regional lymphoscintigraphy being performed in a dog with a single mammary carci-
noma. Technetium was injected in four quadrants around the primary tumor in the cranial abdominal
mammary gland. (B) Gross image of the same tumor in vivo. (C) Regional lymphoscintigram of the
patient highlighting radiopharmaceutical uptake in the mammary tumor and in the sentinel ipsilateral
axillary lymph nodes. (D) Close-up surgical appearance of a “hot” and “blue” sentinel accessory axil-
lary lymph node visualized on the lymphoscintigram enhanced with intraoperative methylene blue
dye mapping. (E) Surgical field highlighting the distance between the mammary tumor and the same
sentinel lymph node.