Anti-Fn amyloid-like FadA antibodies and compositions are provided and methods of treating cancers, including pancreatic and colorectal, and periodontal diseases. Methods include preventing, reducing development, or treating disease in a subject in a subject in need thereof comprising administering to the subject a therapeutically effective amount of an agent which inhibits or blocks an amyloid-like FadA secreted from Fusobacterium nucleatum (Fn).