I saw this book on a shelf at Barnes and Nobles and was immediately struck by its title. Curiosity and caffeine compelled me to pick it up. I knew that naked mole rats never develop cancer and crustaceans only rarely, so I assumed sharks were just another exception. I expected a dissertation on the genetic and biochemical differences between sharks and humans. I did not find this. I stood there and read it in the store, so I can't complain about wasting money on it.
While the title is false, the claim that shark cartilage has interesting pharmacological properties is true. I sincerely doubt any of the other reviewers, either those blindly in favor of or morally opposed to "alternative medicine," have bothered to even skim through the scientific literature. Yes, sharks do develop cancer, but this does not invalidate the fact that shark cartilage does indeed possess antioangiogenic properties and could, in theory, be used as a means of treating tumors.
Shark cartilage is absolutely worthless? A quick search for the key words in a peer-reviewed medical journal of repute will disprove this notion. Nota Bene: shark cartilage taken by mouth, in theory, should not exhibit any profound effects on tumor growth. Those who have recovered miraculously as a result of oral supplementation are probably experiencing a placebo effect or spontaneous remission (neither of which are at all abnormal).