Provided is a simple and safe immunization procedure to reduce cancer incidence and increase longevity by modulating IGF-1 levels in the body. Described are cancer preventive vaccines and methods that elicit circulating antibodies specific to insulin-like growth factor 1 (IGF-1) in the body. Many cancers will be less likely to occur and spread in the absence or reduced levels of the stimulatory signals provided by IGF-1. Longevity also can be extended by immunologically lowering the level of bioavailable IGF-1 in adult animals. This prolongation of lifespan resulting from lower IGF-1 levels is produced independently of the inhibitory effects on carcinogenesis. However, the two IGF-1-mediated processes are linked mechanistically. Methods of active and passive immunization to suppress IGF-1 activity are included. Also described are methods for increasing longevity or reducing one or more symptoms of aging in a warm-blooded animal comprising administering anti-IGF-1 antibodies such that IGF-1 is inactivated or suppressed or administering IGF-1 antigen such that the animal produces endogenous antibodies to IGF-1.