# The Number and Size of Invasion Areas in Mixed-Type Carcinoma in Female Dogs Are Associated with Regional Metastases

## TL;DR

This study shows that the number and size of cancer invasion areas in female dogs' mammary tumors are linked to cancer spread and shorter survival times.

## Contribution

The study introduces histomorphometric analysis of invasive areas as a potential tool for predicting cancer aggressiveness in mixed-type canine mammary tumors.

## Key findings

- Tumors with more and larger invasive areas were more likely to spread to lymph nodes.
- Bitches with invasive areas larger than 2 mm² had shorter survival times.
- No association was found between perimeter/length of invasive areas and cancer markers like Ki67 or HER-2.

## Abstract

Mammary tumors in female dogs can be heterogeneous and difficult to classify. This study looked at specific features of cancer spread in these tumors to see if they could predict how aggressive the cancer would be. By measuring the size and number of cancer invasion areas, researchers found that tumors with more and larger invasion areas were more likely to spread to lymph nodes and were linked to shorter survival times in dogs. These findings suggest that measuring these features could help veterinarians better understand and predict the behavior of these heterogeneous mammary tumors.

Mixed-type carcinoma (MTC) accounts for 44% of mammary neoplasms in bitches and poses challenges in histological grading due to the heterogeneity of invasive areas. The present study aimed to measure and characterize invasive areas in the stroma of MTC and investigate the association of those parameters with lymph node status and survival. Forty cases were analyzed and divided into two groups: with metastasis and without metastasis. The size, perimeter, length, and number of invasive carcinomatous areas were measured. Cases with metastasis showed a higher number of foci (p = 0.003) and larger invasive areas (p = 0.006) compared to cases without metastasis. Bitches with invasive areas larger than 2 mm2 had shorter survival times. No association was found between the perimeter or length of invasive areas, the expression of Ki67, ER, PR, COX-2, HER-2, and the immunophenotype. Thus, the number and size of invasive areas are associated with regional lymph node status, suggesting histomorphometry may serve as a valuable tool for evaluating the biological behavior of mixed-type carcinoma.