The immunohistochemically determined
estrogen receptor (ER) alpha (
ERalpha) and
progesterone receptor (PR) status, as well as recognized, well-accepted prognostic indicators and host factors were prospectively analyzed in 84 cases of primary canine mammary
carcinoma for their effect on disease-free period (recurrence free,
metastasis free, or combined) (
DFP) after an observation period of 18 months. The presence of one or both receptors, as well as
tumor size, lymph node status, histologic grading, intravascular growth, and
necrosis, were of prognostic value for
DFP. In multivariate analysis, only
tumor size and histologic grading proved to be independent prognosticators. None of the host factors analyzed were of prognostic value for
DFP.
ERalpha, PR, or both were detected in 173 out of 228
tumors: 70
ERalpha and PR; 5
ERalpha only; 98 PR only. Statistically significant differences regarding the presence of one or both receptors were observed between benign and malignant
tumors and between complex, mixed, and simple histologic subtypes of benign and malignant
tumors. In the group of malignant
tumors (n=155), the presence of one or both receptors was more frequent in
tumors smaller than 3 cm, without
lymph node metastasis, with tubulopapillary rather than solid patterns of growth among simple
carcinomas, of histologic grades I and II, without both intravascular growth and
necrosis, and with lymphocyte cell infiltrates. The most frequent groups of
hormone receptors-positive
tumors were the
ERalpha-positive and PR-positive group among benign and the
ERalpha-negative and PR-positive group among malignant
tumors.