He noted that sunburn does not necessarily equate with skin cancer risk, but it is a surrogate often used.
▸ Diet. The evidence linking diet to cancer risk is confounding. For example, studies have suggested that a diet high in fat may be associated with an increased cancer risk, but also that saturated fat specifically may be protective.
The soy isoflavone genistein is a potent antioxidant and can block sunburn. However, it probably needs to be used in extremely high concentrations.
“It's a very promising, potential medication, however, in real life I would say buyer beware,” Dr. Spencer said.
▸ Melanin. An Australian company has a patent on an injectable, depot form of melanocyte-stimulating hormone, developed at the University of Arizona, Tucson, that induces a true tan (Melanotan, Epitan Ltd.). The product could prove to be a convenient way to have sun protection, since patients would need a shot only once every few months to have a tan.
However, it could have downsides as well, Dr. Spencer noted. The product could reinforce the idea that tanned skin looks attractive, and that could encourage tanning behavior. Also, it is not known how the hormone might affect existing melanomas.
▸ Polypodium leucotomos. In vitro studies suggest that this extract of a South American fern may be an antioxidant and have antitumor activity.
In one nine-subject study, a single dose significantly increased the minimal erythema dose of the subjects and reduced the levels of histologic markers of malignancy-associated sun damage within a few hours.
“It is not a sunscreen, so the UV light still gets in. For our endocrinology colleagues who are worried about vitamin D, it seems to me this may allow UV-induced, vitamin D production while lowering the UV damage,” Dr. Spencer said.