Dr. Casler is an otolaryngologist at Mayo Clinic's campus in Jacksonville, Florida treating head and neck cancer including skull-based tumors, thyroid cancer including thyroid and parathyroid tumors and jaw tumors. The Mayo Clinic Cancer Center is designated by the National Cancer Institute as a comprehensive cancer center, and is the only NCI-designated comprehensive cancer center with three sites; with campuses in Jacksonville, Florida; Phoenix/Scottsdale, Arizona; and Rochester, Minnesota.