This lecture will provide a review of the 4 most common cancers seen in cats, including lymphoma, mast cell tumors, squamous cell carcinoma, and mammary carcinoma. The lymphoma portion will cover the differences between high grade and low grade lymphoma in cats, as well as discuss this cancer behavior in various locations of the body. We will discuss staging tests and the utility of specialized tests such as flow cytometry and PARR along with the treatment options available. For mast cell tumors, the lecture will provide a summary of mast cell tumor grading in cats as well as review the recommended staging tests and various treatment options available. With feline squamous cell carcinoma and mammary carcinoma, the lecture will provide a summary of the behavior and identification of these cancers including review of the recommended surgical options, staging tests and various treatment options available.