Risk factors such as smoking behind almost half of cancer deaths, finds study

Largest research project of its kind also points to alcohol and being overweight as major contributors

Smoking, drinking alcohol, being overweight and other risk factors are responsible for almost half of all cancer deaths worldwide, according to the largest study of its kind.

Cancer is the second leading cause of death globally, and exposure to risk factors plays a key role in the biology and burden of many cancer types. Doctors do not know the exact causes of cancer, and not every case or death is avoidable, but there are risk factors that can increase people's chance of developing it.