- Medication is made from the cartilage of two shark species
- There is no good evidence that shark cartilage or ingredients of shark cartilage are of benefit for cancer patients
- No major safety concerns have been reported
Shark cartilage is a popular anti-cancer remedy, which is obtained from the cartilage of mainly two shark species.
Even though some basic research suggests that shark cartilage has anti-angiogenic and cytotoxic effects, there is no evidence from five controlled and eight uncontrolled studies to show that it is helpful in the treatment of cancer.
Records of adverse effects exist for the oral supplementation of shark cartilage as well as the injection or enema procedure but no serious events are on record.
The commonly used name for the preparation is shark cartilage. Commercial products are sold as Cartilate, Cartilade, BeneFin, AE-941, U-995, Neovastat, Better Shark MC and numerous other brand names.
Cartilage is part of the skeletal system composed of elastic, translucent tissue. Sharks’ skeletal structure is not made of bones but of cartilage. Shark cartilage is obtained from the spiny dogfish shark Squalus acanthias and the hammered shark Sphyrna lewini and is available in either capsule or powder form. Shark cartilage products contain glycoproteins, such as phyrastitin 1 and 2.
Administration is usually either orally in capsule form or rectally by enemas of shark cartilage mixed with sterile water or by subcutaneous injection but is not normally applied intravenously. From clinical studies we know that for refractory metastatic renal cell carcinoma, a specific water-soluble shark cartilage extract, AE-941 (Neovastat), 60 to 240 mL per day has been used.1,2 For the treatment of solid tumors, 30 to 240 mL daily has been used.3 For cutaneous Kaposi’s Sarcoma, shark cartilage 3,750 to 4,500 mg per day has been used.4 Commercial products typically suggest doses ranging from 500 mg to 4.5g, given in two to six divided doses daily.5
In 1963 it was discovered that tumour growth was partly dependant upon angiogenesis.6 William Lane published a book in 1992 entitled Sharks Don’t Get Cancer.7 The claim is incorrect – sharks can get cancer of their cartilage.8,9 Numerous manufacturers offer commercial preparations available as food supplements, sold without restriction, through various outlets. In 1995, over 40 brands were on the market.
In 2000 Lane was prohibited by the Federal Trade Commission from claiming that “BeneFin or any other shark cartilage product prevents, treats or cures cancer”, until he can provide substantial evidence to support this claim. Since shark cartilage has been promoted as a cancer cure, there has been a measurable decline in shark populations.
It is claimed that a protein in shark cartilage can shrink tumour size, slow or stop the growth of cancerous cells and help reverse bone disease such as osteoporosis.7,10 Providers claim that shark cartilage is effective in cancer because of anti-angiogenic properties. Shark cartilage is also claimed to have antitumor, antioxidant, anti-inflammatory and anti-atherogenic actions, although these putative actions are so far poorly supported by credible clinical research.
Angiogenesis enables new blood vessels and, consequently, tumours to grow. All cartilage, including human, contains anti-angiogenic factors. When shark cartilage is taken orally, they are being digested rather than absorbed into the bloodstream. Therefore no effects after oral administration should be expected.
Some basic research studies have suggested direct toxicity against tumour cells. The inhibition of tumour angiogenesis has been relatively well documented in in-vitro studies One study, for instance, found that tamoxifen has significant anti-angiogenic activity that can be potentiated by shark cartilage.32 Another laboratory study suggested that the development of papillary and solid tumours in mice can be significantly delayed.25
Shark cartilage contains inhibitors of tumour angiogenesis 11-13,34 and immune modulators 14 and may have cytotoxic activity in vitro.35 The polypeptides identified included acidic and basic fibroblast growth factor, angiogenin and transforming growth factors alpha and beta.15 Many of the formulations of commercially available shark cartilage contain little or no anti-angiogenic activity. Furthermore, not all cancers are affected by anti-angiogenic factors. Reliable dose-response data and bioavailability studies are not available.
The popularity of shark cartilage seems to have peaked between 1990 and 2000 but more recent data suggest it is still commonly used by cancer patients.16 Reliable prevalence data are not available. In a survey including 100 patients with various types of cancer shark cartilage was among the most commonly used therapies.17 In an earlier survey including 143 advanced cancer patients, 10.7% of respondents were consuming preparations of shark cartilage.18 More recent survey data imply that 7% of lymphoma survivors use shark cartilage preparations.36 An article in a non-peer-reviewed magazine reports that shark cartilage is a $5 billion-a-year business, with pills and powders sold in health food shops to more than 25.000 people every year.19
Shark cartilage products are marketed as dietary supplements and therefore are not submitted to medicines regulation. Pre-market evaluation and approval by the US Food and Drug Administration (FDA) are not required for dietary supplements. The FDA has not approved of the use of cartilage as a treatment for cancer or any other medical condition. Providers of dietary supplements are not legally permitted to make any claims on the packages of their products for preventing or curing any disease. In practice, such claims are, however, often made via books, websites etc.
A typical course of shark cartilage costs approximately 500 Euros.
AE-941/Neovastat was administered in a randomised phase III trial of BeneFin including 331 patients with advanced solid tumours (including lung, prostate, breast, and kidney tumours).3 They were randomly assigned to receive either 30 to 240 mL/day cartilage or a placebo divided into three to four oral doses a day. Survival was the principal endpoint measured in this trial, but quality of life was also assessed. The results of these trials, however, have not been fully reported. A retrospective analysis involving a subgroup of patients with advanced non-small cell lung cancer suggests that AE-941/Neovastat is able to lengthen the survival of patients with this disease.
Two randomized phase III trials of AE-941/Neovastat in patients with advanced cancer have been approved by the United States Food and Drug Administration (FDA). In one trial in patients with stage III non-small cell lung cancer, treatment with oral AE-941/Neovastat plus chemotherapy and radiation therapy was compared to treatment with placebo plus the same chemotherapy and radiation therapy. Overall survival was not improved in patients taking the shark cartilage preparation 20 In the second trial, treatment with oral AE-941/Neovastat was compared to treatment with placebo in patients with metastatic renal cell carcinoma.21 Results from this second phase III trial have not been reported in the peer-reviewed literature.
Loprinzi published a double-blind, placebo-controlled randomised clinical trial of adjuvant therapy with shark cartilage administered three to four times daily to 83 patients with incurable breast or colorectal cancers.22 The primary endpoint, survival, showed no difference between the patients receiving shark cartilage and those receiving placebo in addition to standard care. Similarly, quality of life showed no inter-group differences.
Another randomised trial suggested an anti-angiogenic effects of shark cartilage in healthy volunteers.23
Several uncontrolled clinical studies have been published, which suggest anti-cancer effects of shark cartilage.24-31 The results of these studies tend to imply that shark cartilage is effective in changing the natural history of various types of cancer or positively influencing related variables. Yet, due to their uncontrolled nature, these investigations cannot establish cause and effect.
Orally, shark cartilage can cause taste disturbances, nausea, vomiting, dyspepsia, constipation, hypotension, dizziness, hyperglycemia, hypoglycemia, hypercalcemia, altered consciousness, decreased motor strength, decreased sensation, erythema, peripheral edema, generalized weakness, fatigue, and decreased performance.1,24,28,30 It might also cause signs of acute hepatitis, including low-grade fever, jaundice, yellowing of eyes, right upper quadrant tenderness, and elevated liver enzymes.33-34
Interactions with the following drugs are conceivable: diuretics, insulin, interferon, thalidomide.
Large variations exist in the purity and concentration of commercially available preparations.
Most recent update and revision in April 2013 by Edzard Ernst.
Fully revised and updated in November 2011 by Edzard Ernst.
Fully revised and updated in April 2010 by Edzard Ernst.
Summary first published in September 2005, authored by Edzard Ernst.