Prognostic value of histologic stage and proliferative activity in canine malignant mammary tumors

E-cadherin expression in canine malignant mammary tumours: relationship to other clinico-pathological variables

The relationship between E-cadherin epithelial expression, as detected by immunohistochemical methods, and other clinico-pathological characteristics of canine malignant mammary tumours was studied in 77 tumours surgically removed from 45 female dogs. The immunohistochemical assessment was based on the estimated percentage of epithelial cells with membranous labelling. Reduction of E-cadherin expression was significantly related to size and ulceration of tumours but not to fixation to skin or underlying tissue; it was also related to lymph node metastasis, necrosis and infiltrative growth. Histological type (but not histological grade) was related to E-cadherin expression, with solid tumours more frequently lacking expression and tubulopapillary tumours showing increased expression as compared with the other types. The significant relationship between E-cadherin and other known factors of poor prognosis suggests that the loss of E-cadherin expression may have prognostic value in canine malignant mammary tumours.

Proliferative Activity, Apoptosis and Expression of Oestrogen Receptor and Bcl-2 Oncoprotein in Canine Mammary Gland Tumours

Samples of 39 canine mammary gland tumours (MGTs) were examined immunohistochemically for oestrogen receptor (ER-alpha), Bcl-2 protein and Ki67 antigen, and by TUNEL assay for apoptosis. ER-alpha was expressed by 80% (31/39) of the tumours, including all of the 15 benign tumours and 67% (16/42) of the malignant tumours. ER-alpha expression was greater in the benign than in the malignant tumours (P<0.01). Bcl-2 protein was detected in 62% (24/39) of the MGTs, of which 67% (10/15) were benign and 58% (14/24) malignant. No significant difference in Bcl-2 expression between benign and malignant tumours was detected. The Ki67 and TUNEL indices were greater in malignant than in benign tumours (P<0.01). Correlation analysis suggested that ER-alpha and Bcl-2 expression were related, but this observation lacked statistical significance. The levels of cell proliferation and apoptosis did not appear to be significantly correlated with the expression of Bcl-2. A positive relationship was apparent between cell proliferation and apoptosis, whilst a negative correlation between ER-alpha and cell proliferation was demonstrated. In conclusion, the suggestion of a positive correlation between ER-alpha and Bcl-2 in canine MGTs indicates that ER may be the regulator of Bcl-2 protein, as in human breast cancer. In contrast to cell proliferation and apoptosis, ER-alpha and Bcl-2 expression were greater in benign MGTs than in their malignant counterparts.

Prognostic and predictive markers in canine tumours: rationale and relevance. A review

Cancer is one of the most common causes of death in dogs. The availability of multiple treatment modalities and novel therapeutic targets make the correct diagnosis, prognostic stratification, and the identification of treatment effect predictive factors an issue of major debate in cancer management. Selection of high and low risk patients and the type of systemic or local treatment is important in cancer management. The search for better prognostic markers and predictive factors is now focused on the molecular mechanisms which underlie tumour behaviour, such as altered cell cycle progression, proliferation, apoptosis, and angiogenesis. The ultimate goal is to identify reliable markers that can accurately diagnose and stage a tumour and predict tumour's clinical behaviour, prognosis and response to therapy. In this review, the current state of prognostication in canine tumours and promising new molecular markers are discussed. The markers are allocated to four groups according to their function: (i) proliferation markers, (ii) apoptosis, (iii) extracellular matrix and cell adhesion molecules, (iv) angiogenesis and (v) cell cycle regulators. Clinicopathological factors and histopathological grading remain the most practical parameters in decision-making. Although experimental research has shown that molecular markers have a good potential to be used as diagnostic, prognostic or predictive markers in canine tumours, insufficient evidence exists on their efficacy for routine use in veterinary oncology.

A prospective analysis of immunohistochemically determined estrogen receptor alpha and progesterone receptor expression and host and tumor factors as predictors of disease-free period in mammary tumors of the dog

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.

Diagnostic pathology for the cancer patient

It is necessary to have a cooperative relationship between the clinician and the pathologist, because information from both is critical for determining the best case management and favorable prognosis. The principle roles of the veterinary pathologist are to describe the submitted tissues, to determine the nature of the tumor, and to assess completeness of surgical margins. Recently, the Council of the American College of Veterinary Pathologists (ACVP) appointed an ad hoc committee on oncology to evaluate oncologists' needs by polling members of the Veterinary Cancer Society (VCS). The committee's vision was to review morphologic, immunologic, and molecular techniques so that veterinary pathologists could meet the current and future diagnostic and prognostic needs of oncologic veterinarians. The factors determined to be most important to the VCS members in selecting a diagnostic pathology provider included, in order of importance: (1) reliability of results; (2) short turnaround-time; (3) easy access for consultation; (4) rapport with pathologist; (5) convenience of service; and (6) cost of service. This manuscript will attempt to review improved morphologic, immunologic, and molecular techniques to provide for the future diagnostic and prognostic needs of oncologic veterinarians.

Canine mammary gland tumors

The National Consensus Group recommends that all women with tumors larger than 1 cm be offered chemotherapy regardless of tumor histology of lymph node status. This recommendation is to ensure that everyone at risk for failing, even though the risk may be low in women with relatively small tumors and favorable histology, has a choice and receives the benefit of adjuvant chemotherapy. This type of treatment recommendation may also be made in dogs based on recognized, well-accepted prognostic factors such as tumor size, stage, type, and histologic differentiation. Based on the limited clinical information available in veterinary medicine, the drugs that are effective in human breast cancer, such as cyclophosphamide, 5-fluorouracil, and doxorubicin, may also have a role in the treatment of malignant mammary gland tumors in dogs. Randomized prospective studies are needed, however, to evaluate the efficacy of chemotherapy in dogs with high-risk mammary gland tumors and to determine which drugs and protocols are the most efficacious. Until such studies are performed, the treatment of canine mammary gland tumors will be based on the individual oncologist's understanding of tumor biology, experience, interpretation of the available studies, and a little bit of gut-feeling. Table 2 is a proposal for treatment guidelines for malignant canine mammary gland tumors according to established prognostic factors, results from published veterinary studies, and current recommendations for breast cancer treatment in women.