By Richard Harkness
Enquirer contributor

Question: First I hear that shark cartilage can prevent or treat cancer, then I hear it can't. Which view is correct?

Answer: The quick answer to your question is that some research suggests shark cartilage shows promise as a cancer fighter. But the complete story is far from in, and the current evidence does not support the heavy marketing of this supplement as a cure for cancer.

First, let's lay to rest one myth: Contrary to widespread belief, sharks do get cancer. Several forms of cancer have been identified in sharks.

Laboratory research indicates that shark cartilage might help prevent angiogenesis (the growth of new blood vessels). Since many cancers need to grow new blood vessels to channel in blood and nourishment, this effect has value in cancer treatment.

Shark cartilage apparently offers no benefit in people with advanced, previously treated cancer, including breast, colorectal, lung, prostate, non-Hodgkin's lymphoma and brain cancer.

One the plus side, preliminary evidence suggests that a particular water-soluble shark cartilage extract, AE-941 (Neovastat), might increase survival time in some patients with kidney cell cancer. There also is anecdotal evidence that shark cartilage might be beneficial for Kaposi sarcoma lesions.

Several preclinical and clinical trials are now evaluating the possible anti-cancer effects of numerous shark cartilage derivatives and extracts.

Neovastat is now under investigation in two Phase III clinical trials (kidney cancer and lung cancer) and one Phase II trial (multiple myeloma).

The kidney cancer trial involves 302 patients who failed to respond to standard immunotherapy treatment, and aims at increasing patient survival time. Results are expected to be reported in early 2003.

The lung cancer trial, with more than 760 participants, hopes to increase survival time for patients taking Neovastat in combination with chemotherapy and radiotherapy. This trial is sponsored by the National Institutes of Health and should be completed in 2005.

No significant safety issues have surfaced in the Neovastat trials. However, there is one reported case of liver inflammation linked to shark cartilage supplements, with full recovery when the supplements were stopped. Other adverse reactions associated with shark cartilage supplementation include stomach upset, constipation, low blood pressure, dizziness, high blood sugar, high calcium blood levels, generalized weakness and fatigue, and neurologic symptoms such as altered consciousness, decreased motor strength and decreased sensation.

Neovastat is a Canadian product that is not yet commercially available, but the company markets a similar product called Angiobalans. Angiobalans is a liquid drink formulation that, according to the manufacturer, can be mixed with juice. (It should be noted that the potency of shark cartilage can decline over time once it is mixed with acidic fruit juices such as orange, apple, grape and tomato. For this reason, it would be best to mix it immediately before use.)

E-mail rharkn@aol.com.