Lung cancer 'link to lack of sun'

Researchers found lung cancer rates were highest in countries furthest from the equator, where exposure to sunlight is lowest.

It is thought vitamin D - generated by exposure to sunlight - can halt tumour growth by promoting the factors responsible for cell death in the body.

The University of California, San Diego study appears in the Journal of Epidemiology and Community Health.

Experts warn that exposure to sunlight is still the major cause of skin cancer - a disease which is on the increase around the world.

Lung cancer kills more than one million people every year around the globe.

The researchers examined data from 111 countries across several continents. They found smoking was most strongly associated with lung cancer rates - accounting for up to 85% of all cases.

But exposure to sunlight, especially UVB light, the principal source of vitamin D for the body, also seemed to have an impact.

The amount of UVB light increases with proximity to the equator. The analysis showed lung cancer rates were highest in those countries furthest away from the equator and lowest in those nearest.

Higher cloud cover and airborne aerosol levels were also associated with higher rates of the disease.