Hyperresistinemia in Obese Female Dogs With Mammary Carcinoma in Benign-Mixed Tumors and Its Correlation With Tumor Aggressiveness and Survival

Abstract

Resistin is associated with metabolic, inflammatory, and neoplastic disorders, and is also considered a prognostic marker in human oncology. Canine mammary tumors have epidemiological, clinical, biological, and genetic characteristics similar to those of women and are proposed as a comparative study model. Here, we evaluate the serum levels of resistin in female dogs with or without mammary carcinoma in mixed tumors (CBMT) and its correlation with the proliferative potential of the tumor, obesity, and survival. Eighty dogs grouped according to the presence (50) or absence (30) of CBMT, reproductive status and body condition were assessed for weight, fat percentage, and canine body mass index. The characteristic of the proliferative potential of the tumor (Ki-67) was evaluated. Ki-67 levels (p = 0.024), staging (p = 0.004), and grade (p = 0.016) influenced the survival of the female dogs. Through a multifactorial analysis, it could be seen that the parameters proliferation index (Ki-67) (p = 0.044) and staging (p = 0.036) influenced the survival of the animals. Neutered and overweight dogs from the control and CBMT groups showed hyperresistinemia. Ki-67 expression and resistin levels in dogs with CBMT were higher in overweight dogs than in dogs with normal weight (p = 0.0001). The survival rate of dogs with CBMT, obese and with high levels of resistin (8,400 μg L^-1) was lower when compared to those with lower levels of resistin. These results showed an important relationship between hyperresistinemia, tumor proliferative potential and excessive body fat, suggesting that resistin levels may act as an interesting prognostic marker in patients with CBMT.

Keywords: Ki-67; adipocytokines; mammary cancer; obesity; prognostic marker; survival.

Figure 1

Microscopical and immunohistochemistry features in mammary carcinoma in mixed tumor (CBMT) of female dogs. (A) CBMT grade I with epithelial portion characterized by irregular tubules coated by discrete pleomorphic cells with scarce cytoplasm, small nuclei, and small foci of infiltrative growth. The myoepithelial cells associated with formation of cartilage and bone trabeculae with foci of mineralization can be observed (highlighted)—HE 10x/40x. (B) CBMT grade II with epithelial portion characterized by irregular papillae and tubules coated by moderately pleomorphic cell layers with sparse cytoplasm, medium, round or ovoid nuclei, vesicular with evident nucleolus. The myoepithelial cells proliferation with myxoid matrix areas can be observed—HE 4x/40x (highlighted). (C) Ki-67 expression in CBMT of female dog in normal body condition (arrow) (D) Ki-67 expression in CBMT of female obese dogs.

Figure 2

Proliferation index (Ki-67) in mammary carcinoma in mixed benign tumor (CBMT) of female dogs and body condition relationship. (A) Correlation between the Ki-67 index and body condition (normal or overweight/obese). (B) Correlation between the Ki-67 index and the reproductive status (not-neutered and neutered).

Figure 3

Resistin levels and body condition relationship. (A) Serum levels of resistin in female dogs with and without mammary carcinoma in benign mixed tumor (CBMT). (B) Serum resistin concentrations in female dogs with mammary carcinoma in benign mixed tumor and presenting normal and overweight/obese body condition.

Figure 4

Hyperresistinemia is associated with body condition. A cutoff was established to distinguish high and low levels of resistin and CBMT animals were divided by their body condition.

Figure 5

Serum resistin concentrations predict disease progression in relation to the survival or death of female dogs carrying CBMT. This situation was analyzed through performance indices, including segregation in scatter plots, ROC (Receiver Operating Characteristic) curve indices, Area Under the Curve/global precision (AUC), Co- positivity (Co-pos), Co-negativity (Co-neg), Positive and negative predictive values (NPV and PPV), as well as negative and positive Likelihood Ratio (LR– and LR+) Performance indices suggested that serum resistin concentrations >8,400 are useful biomarkers to predict survival in female dogs with CBMT.

Figure 6

Survival curves of dogs with CBMT and with normal body condition or overweight/obese. The curves were constructed using the Kaplan-Meier method and compared by the log-rank test.

Figure 7

The influence of the reproductive status in CBMT female dog post-operative survival. The curves included (A) normal weight and (B) overweight/obese dogs. No significant statistical difference could be found for both comparisons, using the long-rank test and with p < 0.05.

Figure 8

Survival curves of CBMT female dogs according to its serum resistin levels. (^*) express a significant statistical difference among the curves by the log-rank test with p < 0.05.