Introduction
Cancer biology is the study of pathologic processes responsible for the genesis of rogue cells, and integrates multiple complementary scientific disciplines including genetics, epigenetics, and intracellular signaling.
Being a disease that affects complex, multicellular organisms, various descriptive terms are used to describe unregulated cell growth including neoplasia, tumor, malignancy, and cancer. While these descriptive terms are not equivalent and connote nuanced differences, they are often used interchangeably by scientists and laypeople alike. Based on biologic behaviors operative locally and distantly, tumors can be categorized as benign or malignant in nature, and correspondingly have different prognoses. Benign tumors are transformed cell populations that grow locally and do not disseminate beyond the site of origination, and respect natural tissue boundaries such as the basement membrane. Conversely, malignant tumors are invasive and breach the normal tissue microenvironment and have the capacity to spread regionally and distantly through lymphatic or hematogenous routes, as well as by direct extension into body cavities.With dramatic improvements in nutrition and preventative medicine practices instituted worldwide, coupled with the progressive age extension of the human and companion animal populations, cancer has risen to being one of the most common causes of mortality. In the USA and other developed countries worldwide, cancer remains the second leading cause of death, only exceeded by heart disease, with one out of four people dying because of uncontrolled cancer progression. Similarly, the most common pathophysiologic process causing deaths in adult dogs (>1 year old) is the development of cancer (Fleming et al., 2011), with one out of three adult dogs dying from this single pathologic condition. Interestingly, the predisposition to develop cancer appears to be enriched in canines, and likely an unintended by-product of selective breeding practices for specific phenotypic traits.
Based on the substantive fraction of human beings and companion animals that suffer and subsequently succumb to cancer, a strong and clinically warranted impetus exists for studying tumor biology. With focused initiatives that incorporate scientists and clinicians from diverse professional disciplines, it is anticipated that new knowledge will be generated that better elucidates the molecular underpinnings of cancer. Excitingly, over the past two decades, there has been continued prominence and scientific value ascribed to the discipline of comparative oncology, and pet dogs and cats are now viewed as valuable translational models for studying cancer biology and therapeutics (Oh & Cho, 2023; LeBlanc & Mazcko, 2020). Through the concerted efforts on both human and companion animal sides, rapid advances in knowledge are being made in cancer biology and promise to improve the prevention, diagnosis, and treatment of the most lethal cancer histologies.