The impact of smoking on several cancers is well known, but heavy drinking, unsafe sex, low fruit and vegetable intake, obesity, lack of exercise, contaminated injections and indoor smoke from fuels are also risks that could be reduced. Majid Ezzati of the Harvard School of Public Health in Boston and colleagues suggest in the Lancet that health interventions could prevent a “substantial proportion” of the 7 million cancer deaths a year, and be more effective in reducing mortality than screening and ever-improving treatments.
Smoking is a factor in 21% of all cancer deaths, especially in men, they say, with high alcohol and low fruit and vegetable intake accounting for 5% each. Sexual transmission of the human papilloma virus is a leading risk factor for cervical cancer in low- and middle-income countries, especially where screening is limited, although there are hopes that vaccines will soon be widely available.
The researchers say smoking is linked to 856,000 deaths a year from lung, bronchial and tracheal cancers, 184,000 oesophageal cancers and 131,000 oral cancers. About 116,000 oesophageal cancer deaths and 51,000 oral cancer deaths are linked to alcohol. They based their figures on a review of published studies, government reports and international databases, as well as a reanalysis of primary data. Problems with missing information meant they did not include other factors such as occupational risk or exposure to ultraviolet light and passive smoking.