Melanoma,
also known as malignant melanoma, is a type of cancer that develops from the
pigment-containing cells known as melanocytes. Melanomas typically occur in the
skin but may rarely occur in the mouth, intestines, or eye. Melanomas are
usually caused by DNA damage resulting from exposure to ultraviolet (UV) light
from the sun. Genetics also play a role. About 20-25% develop from moles where
a history of affected family members, or ones with poor immune function are at
greater risk.
Melanoma is
the most dangerous type of skin cancer. Treatment is typically removal by
surgery. In those with slightly larger cancers nearby lymph nodes may be tested
for spread. Most people are cured if spread has not occurred. In those in whom
melanoma has spread, immunotherapy, biologic therapy, radiation therapy, or
chemotherapy may improve survival. The likelihood that it will come back or
spread depends how thick the melanoma is, how fast the cells are dividing, and
whether or not the overlying skin has broken down.
Researchers
at Sahlgrenska Academy, University of Gothenburg, demonstrated in January 2014
that antioxidants hastened and aggravated the progression of lung cancer. Mice
that were given antioxidants developed additional and more aggressive tumors.
Experiments on human lung cancer cells confirmed the results. The group now report
that antioxidants in mice double the rate of metastasis in malignant melanoma. Mice
that were given antioxidants developed additional and more aggressive tumors. One
of the fastest expanding types of cancer in the developed world, malignant
melanoma has a high mortality rate - which is one reason that researchers at
Sahlgrenska Academy were so anxious to follow up on the lung cancer studies.
Their findings
reveal the following:
a: As
opposed to the lung cancer studies, the primary melanoma tumor was not
affected.
b: Antioxidant boosted the ability of the tumor
cells to metastasize.
c: Metastasis is the cause of death in the case of
melanoma.
d: The
primary tumor is not dangerous per se and is usually removed.
Free radicals
are believed to cause cancer, and there is large volume of literature to
support this theory. So it was simply assumed that antioxidants, which destroy
free radicals, provide protection against the disease. Found in many
nutritional supplements, antioxidants are widely marketed as a means of
preventing cancer. The researchers from University of Gothenburg have added a
condition apply logo to use of antioxidant which now says “antioxidants protect
healthy cells from free radicals that can turn them into malignancies but may
also protect a tumor once it has developed”. Moreover, experiments on cell
cultures from patients with malignant melanoma confirmed the new results.
The authors
conclude “Our current research combined with information from large clinical
trials with antioxidants suggests that people who have been recently diagnosed
with cancer should avoid such supplements.”
The next task
for this group is study the roles of lotions in melanoma progression as skin
and suntan lotions sometimes contain beta carotene or vitamin E, both of which
could potentially affect malignant melanoma cells in the same way as
antioxidants in nutritional supplements.
Article Citation: Bergo, M. O.; et. al. Antioxidants can increase melanoma metastasis in mice.
Science Translational Medicine 2015,
7(308), 308re8. DOI:
10.1126/scitranslmed.aad3740
