Cancer rates double in 30 years

Breast and lung cancer rates have doubled worldwide since 1975, according to a study published today.

More than 1.1m cases of breast cancer are now diagnosed across the world each year compared with about 500,000 cases in 1975, according to researchers from Cancer Research UK who analysed a global database of 27 cancers.

They said that most of the increase is accounted for by the increased life expectancy among women worldwide together with the world's growing population, which has risen from 4bn in 1975 to around 6.3bn today.

Lung cancer is the most commonly diagnosed cancer in the world, with approximately 1.4m new cases every year compared to fewer than 600,000 in 1975.

Most cases are thought to be smoking related. In the developing world lung cancer rates are found to follow smoking rates, with incidence of the disease tending to peak about 20 years after the proportion of people smoking peaks.

Countries such as the UK, where smoking has declined among men and has peaked among women, are seeing big falls in the numbers of people being diagnosed with lung cancer.

But in regions of the world where the prevalence of smoking has increased, such as eastern Africa, central America and south-east Asia, researchers predicted a large increase in lung cancer rates over the next 20 years.

John Toy, Cancer Research UK's medical director, said: "These statistics still show that cancer is still essentially a major disease of the developed world. Only 4% of deaths in Africa are due to cancer, compared with 19% in Europe.

"The developing world can learn from past mistakes: tackling the smoking habit, for example, would minimise future lung cancer cases and substantially reduce the future cancer burden in developing countries."

More positively, the report noted a fall in rates of stomach cancer, the most common form of the disease in 1975.

Cervical screening programmes in developed countries have significantly reduced the number of women being diagnosed with cervical cancer, although cases are still rising in areas with fast-growing populations.

Overall, in the UK, although cancer rates are on the increase, mortality rates are falling due to earlier diagnosis and better treatment.

Professor Toy said: "Although these figures show a persistent increase in the number of people in the world being diagnosed with cancer, developing and refining new treatments will continue to improve the chances of surviving.

"Already, thanks to such research, many more people diagnosed with cancer in 2005 will survive compared to those diagnosed in 1975."