Seven million people's cancer could be prevented each year, according to the first global analysis.

A report by World Health Organization (WHO) scientists estimates 37% of cancers are caused by infections, lifestyle choices and environmental pollutants that could be avoided.

This includes cervical cancers caused by human papilloma virus (HPV) infections which vaccination can help prevent, as well as a host of tumours caused by tobacco smoke from cigarettes.

The researchers said their report showed there is a "powerful opportunity" to transform the lives of millions of people.

Some cancers are inevitable - either because of damage we unavoidably build up in our DNA as we age or because we inherit genes that put us at greater risk of the disease.

But researcher Dr Isabelle Soerjomataram said "people are surprised to hear" that nearly four in 10 cancers can be prevented as it is "a substantial number".

The International Agency for Research on Cancer, part of the WHO, analysed 30 preventable factors known to increase the risk of cancer.

These include smoking and ultraviolet (UV) radiation which can directly damage our DNA; obesity and too little physical activity which alter inflammation and hormones in the body to raise cancer risk; and air pollution which can wake up dormant cancer cells.

The agency's report also looked at nine cancer-causing infections including HPV, hepatitis viruses which lead to liver cancer and the stomach bug H. pylori.

The team used data on cancer cases from 2022 and from the 30 risk factors a decade earlier – across 185 countries - to perform their statistical analysis.

The big three contributors to more than 18 million cancer cases around the world were found to be:

smoking tobacco which caused 3.3 million cancers

infections causing 2.3 million cancers

alcohol use leading to 700,000 cancer. (BBC)

• PHOTO; Air quality around the Delhi region of India reached 'severe' levels in November. Photo courtesy of the BBC