The present invention provides a method of treating a cancer using a neurotoxin, preferably Botulinum toxin (“BTX”). The application of a neurotoxin around a cancer acts to decrease the contractile forces of the muscles surrounding a neoplasm which normally squeeze cancer cells through efferent channels leaving the cancer vicinity to distant sites. Also, the application of the toxin at sites distant from the cancer enhances cellular and humoral immunologic functions which further contributes to cancer cell death and spread. Following administration of botulinum toxin around and distant to a cancer, it is noticed that local, regional, and distant spread is reduced or eliminated. Immunomodulation with botulinum toxin is also valuable in treating other disease that may or may not be associated with cancers, such as viral-induced growths, viral conditions, fungal disease, chronic wounds, graft versus host disease, autoimmune disease, and HIV.