Immunohistologic detection of estrogen receptor alpha in canine mammary tumors: clinical and pathologic associations and prognostic significance.
Eighty-nine canine mammary tumors and dysplasias of 66 bitches were investigated to determine the immunohistochemical expression of classical estrogen receptor (ER-alpha) and its clinical and pathologic associations and prognostic value. A complete clinical examination was performed and reproductive history was evaluated. After surgery, all animals were followed-up for 18 months, with clinical examinations every 3-4 months. ER-alpha expression was higher in tumors of genitally intact and young bitches (P < 0.01, P < 0.01) and in animals with regular estrous periods (P = 0.03). Malignant tumors of the bitches with a previous clinical history of pseudopregnancy expressed significantly more ER-alpha (P = 0.04). Immunoexpression of ER-alpha decreased significantly with tumor size (P = 0.05) and skin ulceration (P = 0.01). Low levels of ER-alpha were significantly associated with lymph node involvement (P < 0.01). Malignant tumors had lower ER-alpha expression than did benign tumors (P < 0.01). Proliferation index measured by proliferating cell nuclear antigen immunostaining was inversely correlated with ER-alpha scores (P = 0.05) in all tumors. Low ER-alpha levels in primary malignant tumors were significantly associated with the occurrence of metastases in the follow-up (P = 0.03). Multivariate analyses were performed to determine the prognostic significance of some follow-up variables. ER-alpha value, Ki-67 index, and age were independent factors that could predict disease-free survival. Lymph node status, age, and ER-alpha index were independent prognostic factors for the overall survival. The immunohistochemical detection of ER-alpha in canine mammary tumors is a simple technique with prognostic value that could be useful in selecting appropriate hormonal therapy.
Nieto
A
A
Department of Animal Pathology II, Veterinary School, Universidad Complutense de Madrid, Spain. ananieto@eucmax.sim.ucm.es
Peña
L
L
Pérez-Alenza
M D
MD
Sánchez
M A
MA
Flores
J M
JM
Castaño
M
M
D000818:Animals; D002369:Castration; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D047628:Estrogen Receptor alpha; D005260:Female; D005500:Follow-Up Studies; D019394:Ki-67 Antigen / Q000032:analysis; D015674:Mammary Neoplasms, Animal / Q000737:chemistry* / Q000473:pathology; D011379:Prognosis; D011960:Receptors, Estrogen / Q000032:analysis*
D047628:Estrogen Receptor alpha; D019394:Ki-67 Antigen; D011960:Receptors, Estrogen