Despite the huge numbers of people now using mobile phones, there hasn't been a corresponding increase in brain cancers, researchers say.

If mobile phones are supposed to increase the risk of brain tumours, there is no evidence of it in cancer statistics in New Zealand, research shows.

That's despite the explosion in numbers of people using mobile phones.

Cancer expert Mark Elwood says there have been concerns using mobile phones could lead to an increase in the frequency of brain tumours.

"Several major international studies have suggested either no risk or a slightly increased risk in high users, while some others have suggested substantial risks."

New Zealand's first commercial mobile phones were introduced in 1983 and in 1995, it was estimated 10 per cent of the population had mobile phones.

Last year, it was estimated 71 per cent of those aged 18 to 54 and 37 per cent over 55s had mobile phones.

Professor Elwood's research team went through the cancer statistics in New Zealand from 1995 to 2010 to see if there was a corresponding increase in brain cancers, but found no general increase.

"In fact, for the wide age range 10 to 69 years, there has been a decrease of about one per cent per year."

The research added to the evidence there wasn't a substantial increased risk in mobile phone users - which was consistent with most similar studies in other countries, he said.

However, he warned the type of study could not exclude a small risk, or one limited to a certain subtype of cancers. Cancers also might arise after more than about 15 years of phone use.

They did not know why brain cancer figures were decreasing in New Zealand.

The research was published in the Australia and New Zealand Journal of Public Health.