Public Health

One third of cancer deaths due to modifiable risk factors

Last Updated: 2005-11-17 18:30:19 -0400 (Reuters Health)

By Karla Gale

NEW YORK (Reuters Health) - Thirty-five percent of cancer deaths worldwide can be attributed to the effect of nine modifiable risk factors, according to results of a large collaborative study.

Although screening and treatment has reduced mortality from some cancers, "primary prevention through lifestyle and environmental interventions might offer the best option for reducing the large and increasing burden of cancers worldwide," Dr. Majid Ezzati and colleagues opine in their report, published in the November 19th issue of The Lancet.

However, they add, "policies and programmes to implement such interventions depend on reliable and comparable analyses of the effect of risk factors for cancer at the population level."

To that end, Dr. Ezzati, from Harvard School of Public Health in Boston, and his team systematically reviewed published studies, government reports, and international databases to obtain data on risk factor exposure and to estimate population attributable fractions.

Of 7 million global deaths from cancer in 2001, the authors estimate that 2.43 million can be ascribed to the nine risk factors: overweight and obesity, low fruit and vegetable consumption, physical inactivity, smoking, alcohol consumption, unsafe sex, urban air pollution, household use of solid fuels, and contaminated injections in health-care settings.

In high-income and low-income countries alike, smoking and alcohol use were the most prevalent preventable causes of cancer deaths. In low-and-middle-income countries, low fruit and vegetable intake were also significant causes of cancer mortality, while in high-income countries, overweight and obesity were among the most important causes.

"About a quarter of cancer deaths could be prevented by reducing tobacco and alcohol use," Dr. Ezzati said in an interview with Reuters Health. "Those are the ones for which there has been good experience with interventions, such as taxation, prohibiting smoking in public places, limiting advertising to minors, and reducing the initiation of smoking and alcohol abuse."

For risk-factor attributable deaths, 37% were from lung cancer, 12% from liver cancer, and 11% from esophageal cancer, the investigators report, all of which have 5-year survival rates of < 25%.

Although high-income countries have only 15% of the world's population, they accounted for 31% of deaths due to modifiable risk factors. Except for cancer of the uterine cervix, joint population attributable fractions were greater in high-income countries than in low-and-middle-income countries for all other cancer sites.

"We hope that, given the huge interest society has in cancer prevention, that this study will motivate policies to reduce risks," Dr. Ezzati concluded.

Lancet 2005;366:1784-1793.