Ninety per cent rise in melanoma in Maori

Just released research shows the incidence of malignant melanoma in Maori has nearly doubled.

The 90 per cent increase during an 11-year period of research compares with a 12 per cent increase in the incidence among Pakeha.

The startling change could be due to inter-marriage changing skin colour, according to researchers at Otago University's Hugh Adam cancer epidemiology unit.

These changing skin "phenotypes" can account for a wide range of skin pigmentation within an ethnic group.

"There are fair-haired, fair-skinned people who identify as Maori," said researchers Dr Mary Jane Sneyd and Dr Brian Cox.

Other contributing factors could be the development of different types of melanoma in different ethnic groups, or increased UV radiation due to increased sun exposure over time.

The thinning Antarctic ozone layer was blamed for a 12 per cent increase in New Zealand's peak sunburning UV radiation over the 1990s, with larger increases seen for DNA-damaging UV radiation and plant-damaging UV radiation.

The researchers also found Maori in New Zealand have a greater proportion of "thick" tumours -- melanoma to a depth greater than 1mm -- than the European population here.

Tumour thickness or depth at time of diagnosis is a major factor in the risk of death from melanoma.

The rate of nodular melanoma (which tend to be thick melanoma) in Maori (15.9 per cent) is second only to the rate of nodular melanoma found in Pacific Islanders in this country (17.1 per cent).

But Dr Sneyd and Dr Cox they also noted that the overall melanoma incidence rates in Pacific Islanders were much lower than those in Maori.

The findings, published last month in the international journal Cancer Epidemiology, Biomarkers and Prevention are similar to United States research which also shows increasing rates of melanoma among non-white populations there.

Maori still only have about 10 per cent of the incidence rate of cutaneous melanoma, compared to European New Zealanders with fair skin and fair hair.

"While there remains overall a substantially lower risk of melanoma for Maori, Pacific and Asian people than for fairer-skinned Europeans, this research suggests the need for Maori to be more aware of their potential risk, protect themselves from sunburn and to take any new or changing skin lesions to their doctor," the researchers said.

- NZPA