Receptor gene linked to melanoma risk

A variation of the gene responsible for metabolising vitamin D appears to increase the risk of melanoma, a serious and sometimes fatal skin cancer, Italian researchers report.

The authors believe that the altered form of the receptor is less able to bind to vitamin D, a vitamin that can be produced in sun-exposed skin. Prior research has suggested that this binding helps protect against melanoma.

Variants in the vitamin D receptor gene have been hypothesised to affect the risk of melanoma, but findings from prior studies have been conflicting.

The current investigation represents the first combined analysis performed using published data, according to a report in an upcoming issue of the American Cancer Society's journal Cancer.

Data from six studies, which included a total of 2152 patients with melanoma and 2410 subjects without the cancer, were included in the analysis.

Vitamin receptors

Together, the studies examined the impact of five vitamin D receptor gene variations, or "variants," designated TaqI, FokI, BsmI, EcoRV, and Cdx2, on the risk of melanoma.

Patients with the BsmI variant had a 30% increased risk of melanoma, report Dr Simone Mocellin and Dr Donato Nitti, from the University of Padua. This would account for close to 10% of melanoma cases.

The FokI variant did not affect the risk of melanoma and the impact of the other three variants was less clear.

The authors conclude that although the effects of the BsmI variant are not fully known, "these findings indirectly support the hypothesis that sun exposure may have an anti-melanoma effect through activation of the vitamin D system."

But they add that additional research is needed, calling for a larger study to "test whether any vitamin D receptor is independently associated with melanoma risk."

Boosting vitamin D

Professor Bruce Armstrong of the University of Sydney, who was not part of the study, says there is a growing body of evidence supporting the link between low levels of vitamin D and melanoma.

"There are some interesting links out there," says Armstrong. "We know that people who have less active receptors seem to be at higher risk [of developing melanomas]."

"That suggests vitamin D is quite important in preventing melanoma in the first place."

Armstrong says that people with a less effective BsmI gene would benefit from an increased amount of the vitamin D.

But he says there is debate over how to increase vitamin D levels, with countries such as the United States advocating the use of oral supplements.

"In Australia we've tended to accept the view that a small amount of direct UV (ultraviolet light) is beneficial," says Armstrong.

But he warns that this should be done in moderation.

"You don't need large amounts ... and should only be in the sun when the UV index is below 3," Armstrong says.

Source: abc.net