Shark cartilage can't cure cancer, say scientists

- Last updated on GMT

Related tags: Chemotherapy, Oncology, Cancer

When the mass media reported, more than a decade ago, on studies
purporting to show that shark cartilage could send cancer into
remission, medical professionals didn't really buy it. Now it seems
their skepticism was well placed, writes Jess Halliday, as a
new study finds it improves neither the survival prospects nor the
quality of life of advanced-stage cancer patients.

Mayo Clinic Oncologist Charles Loprinzi and colleagues in the North Central Cancer Treatment Group carried out a randomized, placebo-controlled, double-blind, clinical trial involving 83 patients with incurable breast or colorectal cancer, who had good performance status and organ function.

The results are published in the July 1 issue of the American Cancer Society's peer-reviewed journal CANCER​, now online.

The patients were randomly assigned to one of two groups. One group took a shark cartilage product three to four times each day, and the other took a placebo with identical smell and appearance. Both groups also received standard medical treatment, such as chemotherapy.

The primary aim of the study was to find out whether shark cartilage boosted patients' survival, and the secondary aim was to evaluate toxicities, tolerability, and any quality of life benefits it might deliver.

However Loprinzi's team found shark cartilage to be a failure on all counts. There was no difference in survival rates between the two groups, nor any discernible benefit to quality of life. In fact, in some cases in the cartilage group, quality of life was seen to deteriorate.

The researchers also note that the first month of the trial was marked by a high dropout rate in the shark cartilage group due to toxicity.

According to the researchers, the reputed benefits of shark cartilage stem from the claim that sharks rarely get cancer because their bodies contain a lot of cartilage.

But all the studies conducted to date have produced ambiguous results - bar the 1993 study carried out in Cuba, which captured media attention worldwide with its claims that patients with advanced cancer had gone into remission after taking shark cartilage.

This trial was never published in a peer-reviewed medical journal, however, and the National Cancer Institute dismissed the results as "incomplete and unimpressive".

Since then, medical professionals have sought to discourage the use of this particular complementary or alternative approach. In 2002 the British Journal of Cancer​ published an editorial warning that websites offering patients alternative therapies, including shark cartilage, could pose a greater risk to their health as they might cause them to neglect orthodox approaches.

Related topics: Research, Cancer risk reduction

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