The study appears in this week's New England Journal of Medicine.
Common warts are noncancerous growths caused by various strains of human papilloma virus, explains lead researcher Lotta Gustafsson, MSc, a microbiologist with the University of Lund, Sweden. Depending on the virus strain, the warts may be killed by salicylic acid or other treatments. However, some warts continue thriving despite rigorous treatment.
The tumor-killing properties of a protein complex called a-lactalbumin-oleic acid -- which contains a protein found in breast milk -- were discovered by chance in earlier experiments, she writes. The protein has "unusual properties that enhance its potential as a new therapeutic agent."
In fact, preliminary studies involving rats have even suggested that the protein may affect tumor cells. However, that has not yet been tried in humans, she writes.
The protein complex "activates several aspects of cell-death machinery" -- becoming absorbed into tumor cells, disrupting activity, and causing cell death, Gustafsson explains. Healthy cells are not affected.
Gustaffsson and her colleagues describe their study of 40 patients with common skin warts that no conventional treatment could eradicate.
In the three-week study, the patients got either a daily skin treatment of the breast milk protein complex or a placebo treatment. Researchers measured wart size to document changes in the volume of the lesions.
They showed that in 100% of the breast milk group, most warts decreased in size by at least 75% after three weeks of treatment, compared with only a 15% decrease in size in a few warts in the placebo group.
After the first three weeks, people in the placebo group were allowed to receive the protein complex treatment. After receiving the treatment, their lesions also responded. The treatment resulted in an 82% reduction in the size of warts. With time, all lesions completely disappeared in people who received the protein complex.
Two years later, 38 of the original 40 patients were wart-free, reports Gustafsson.
Because there were no side effects -- and because the protein kills only tumor cells -- the protein "has potential as a novel therapeutic tool in the treatment of [warts] and other tumors," she writes.
SOURCE: Gustafsson, L. New England Journal of Medicine, June 24, 2004; vol 350: pp 2603-2672.