The antitumor potential of cartilage has been investigated extensively in laboratory and animal studies. Some of these studies have assessed the toxicity of cartilage products toward cancercellsin vitro.[1,2] Reviewed in [3,4,5,6]
The clinical utility of the test refers to the likelihood that the test will, by prompting an intervention, result in an improved health outcome. The clinical utility of a genetic test is based on the health benefits related to the interventions offered to people with positive test results. Theoretically, there are at least five strategies that might improve the health outcome of people with a genetic susceptibility to cancer:
Correction of the underlying genetic defect (not currently available)...
In one study, cells from 22 freshly isolated human tumors (nine ovary, three lung, two brain, two breast, and one each of sarcoma, melanoma, colon, pancreas, cervix, and testis) and three human cultured cell lines (breast cancer, colon cancer, and myeloma) were treated with Catrix, which is a commercially available powdered preparation of bovine (cow) cartilage. Reviewed in [3,4,6] In the study, the growth of all three cultured cell lines and cells from approximately 70% of the tumor specimens were inhibited by 50% or more when Catrix was used at high concentrations (1-5 mg/mL of culture fluid). However, it is unclear whether the inhibitory effect of Catrix in this study was specific to the growth of cancer cells because the preparation's effect on the growth of normal cells was not tested. In addition, the cytotoxic component of Catrix has not been identified, and it has not been shown that equivalent inhibitory concentrations of this component can be achieved in the bloodstreams of patients who may be treated with either injected or oral formulations of this product. (Refer to the Human/Clinical Studies section of this summary for more information.)
A commercially available preparation of powdered shark cartilage (no brand name given) was reported to have no effect on the growth of human astrocytoma cells in vitro. The shark cartilage product tested in this study, however, was examined at only one concentration (0.75 mg/mL).
The immune system-stimulating potential of cartilage has also been investigated in laboratory and animal studies. In one study, Catrix was shown to stimulate the production of antibodies by mouse B cells (B lymphocytes) both in vitro and in vivo. However, increased antibody production in vivo was observed only when Catrix was administered by intraperitoneal or intravenous injection. It was not observed when oral formulations of Catrix were used. In most experiments, the proliferation of mouse B cells (i.e., normal, nonmalignant cells) in vitro was increasingly inhibited as the concentration of Catrix was increased (tested concentration range, 1-20 mg/mL). Catrix has also been reported to stimulate the activity of mouse macrophagesin vivo, Reviewed in [3,6] but results demonstrating this effect have not been published.
The effects of shark cartilage on the immune system were also reported in two studies that used the same purified protein fraction that had exhibited the most immunostimulatory effects when tested.[8,9] One study explored the effects of this fraction on tumor immune response by observing the infiltration of this fraction on CD4 and CD8 lymphocytes in a murine tumor model. An increase in the ratio of CD4/CD8 lymphocytes was seen in tumor-infiltrating lymphocytes but not in peripheral blood lymphocytes. The second study exploring immune system response measured antibody response, cytotoxic assay, lymphocyte transformation, and intratumor T-cell ratio in mice. The fraction exhibited the ability to augment delayed-type hypersensitivity response against sheep red blood cells in mice and to decrease the cytotoxic activity of natural killer cells. In addition, this fraction showed a strong inhibitory effect on human brain microvascular endothelial cell proliferation and migration in the fibrin matrix.