It has been falsely assumed that sharks do not get cancer. This has lead to the medicinal use of shark cartilage to treat some cancers or reduce tumor growth. Although sharks have a low incidence of cancer, tumors and cancer have been identified in sharks. A study published in the Journal Cancer by Dr. Ostrander et al. of Johns Hopkins University titled Shark Cartilage, Cancer and the Growing Threat of Pseudoscience indicates that the promotion of crude shark cartilage extracts as a cure for cancer has contributed to at least two significant negative outcomes: a dramatic decline in shark populations and a diversion of patients from effective cancer treatments.