Growing evidence across human and animal oncology demonstrates that the tumor microenvironment plays a decisive role in cancer progression, metastasis, and therapeutic response. In canine mammary gland carcinoma, however, prognostic assessment has traditionally relied on tumor grade and stage, which alone may fail to identify dogs at high risk of recurrence or metastasis.
In this study, investigators evaluated whether collagen density, organization, and fiber morphology within canine mammary tumors could serve as prognostic biomarkers. Using second harmonic generation imaging, the researchers quantitatively analyzed fibrillar collagen features in grade I/II and grade III canine mammary carcinomas.
Multiple collagen-related parameters were examined, including collagen density, the presence or absence of a tumor–stromal boundary, tumor-associated collagen signatures, and individual fiber characteristics such as width, length, and straightness. These structural features were then correlated with clinical outcomes.
The results revealed that increased collagen density and greater fiber width, length, and straightness were all inversely correlated with overall survival time. Notably, high-grade tumors were significantly less likely to exhibit a clearly defined tumor–stromal boundary, and the absence of this boundary predicted poor prognosis.
Importantly, two collagen features—the lack of a tumor–stromal boundary and increased collagen fiber width—remained strong predictors of decreased survival even after controlling for tumor grade, clinical stage, ovariohysterectomy status, and lymphovascular invasion in multivariable statistical models.
These findings demonstrate that stromal architecture provides independent prognostic information beyond conventional histopathologic criteria. Incorporating collagen signatures into diagnostic evaluation could therefore improve identification of canine patients who may benefit from adjuvant therapy.
Beyond veterinary oncology, the study reinforces the value of the dog as a translational model for human breast cancer. The parallels between canine and human mammary tumor collagen organization support the use of naturally occurring canine cancers to study tumor–stromal interactions and to evaluate potential stromal-targeted therapies.
Source: Case, A., Brisson, B. K., et al. (2017). Identification of prognostic collagen signatures and potential therapeutic stromal targets in canine mammary gland carcinoma. PLoS ONE, published July 6, 2017.
