First, here is the issue.
Three principal mechanisms of action have been proposed to explain the antitumor potential of cartilage: 1) it kills cancer cells directly; 2) it stimulates the immune system; 3) it blocks the formation of new blood vessels (angiogenesis), which tumors need for unrestricted growth.
Second, a quick review of the literature...
Title: Phase I/II trial of the safety and efficacy of shark cartilage in the treatment of advanced cancer.
AU: Miller-DR; Anderson-GT; Stark-JJ; Granick-JL; Richardson-D
SO: J-Clin-Oncol. 1998 Nov; 16(11): 3649-55.
CONCLUSION: Under the specific conditions of this study, SC [shark cartilage] as a single agent was inactive in patients with advanced-stage cancer and had no salutary effect on quality of life.
Title: Shark cartilage extract interferes with cell adhesion and induces reorganization of focal adhesions in cultured endothelial cells.
AU: Chen-JS; Chang-CM; Wu-JC; Wang-SM
SO: J-Cell-Biochem. 2000 Jun 6; 78(3): 417-28.
CONCLUSION: Shark cartilage chondroitin sulfate had no inhibitory effect on either cell attachment or spreading of endothelial cells.
I don't want to bore readers, but I found dozens of other journal articles with similar results. OTOH, some studies have found positive results. From Morris, Coderre, Micca, et al: "It was concluded that shark cartilage, when given alone, significantly increased the survival time of tumour-bearing rats, presumably owing to an anti-angiogenic effect."
Third, as of 1/1/2001, only three human studies have been published to date, and the results are inconclusive about the effectiveness of cartilage as a treatment for cancer.
Finally, research is in its infancy, so it is premature to make conclusions about shark cartilage. Given current evidence, to answer your question, there currently is no conclusive proof of the efficacy of shark cartilage. Eventually, studies with sufficient statistical power will render a verdict. However, if you believe in it, then the palliative effects may be worth a try.
Rajeeb.
Epidemiologist and Data Manager
MSPH, BS