A big part of understanding cancer is understanding the cellular environment itthrives in by analyzing it from a microecological perspective. Humans and other species are affected by different cancer types, and this highlights the notion that there may be a correlation between specific tissues and neoplasia prevalence. Research shows that humans are the most susceptible to adenocarcinomas and carcinomas which include the following tissues: lungs, breast, prostate, and pancreas. Furthermore, research shows that adenocarcinoma accounts for 38.5% of all lung cancer cases, 20% of small cell carcinomas, and 2.9% of large cell carcinoma. The incidence of the most common cancer types in humans is consistently increasing annually. This study analyzes trends of tissue-specific cancers across species to examine possible contributors to vulnerability to cancer. I predicted that adenocarcinomas would be the most prevalent cancer type across the tree of life. To test this hypothesis, I reviewed over 130 species that reported equal to or greater than 50 individual necropsy pathology records across 4 classes (Mammalia, amphibia, Reptilia, Aves) and ranked them by neoplasia prevalence. This information was then organized in tables in descending order. The study’s resulting tables and data concluded that the hypothesis was correct. I found that across all species adenocarcinomas were the most common cancer type and account for 30.4% of malignancies reported among species. Future research should investigate how organ size contributes to neoplasia prevalence.