October 12, 2005

Smoking: the top preventable cause of cancer deaths

By Megan Rauscher

NEW YORK (Reuters Health) - In the year 2000, about 1.4
million cancer deaths, or more than one in every five cancer
deaths worldwide, were caused by smoking, "making it possibly
the single largest preventable cause of cancer death," Dr.
Majid Ezzati from Harvard School of Public Health in Boston
told Reuters Health.

Smoking is widely recognized as a major cause of cancer;
but there is little information on how it contributes to the
global and regional burden of cancers in combination with other
risk factors that affect background cancer mortality patterns,
Ezzati and colleagues point out in the latest issue of the
International Journal of Cancer.

To estimate site-specific cancer deaths caused by smoking
in the year 2000, they analyzed data from two unique data
sources -- the American Cancer Society's Cancer Prevention
Study II and the World Health Organization and International
Agency for Research on Cancer (IARC) cancer mortality

There were an estimated 1.42 million cancer deaths
worldwide in 2000. Twenty-one percent of total global cancer
deaths were attributed to smoking.

Of these, 1.18 million were among men and 0.24 million
among women. "The proportion of cancer deaths caused by smoking
is more than 40 percent for men in many regions of the world
like North America and Europe," Ezzati said.

A total of 625,000 smoking-caused cancer deaths occurred in
the developing world and 794,000 in industrialized regions.

Right now, there are slightly more cancer deaths caused by
smoking in the industrialized countries of North America,
Europe, and Western Pacific, Ezzati observed, "but the rise in
smoking in the developing world in the past two to three
decades is expected to shift the burden to the developing

Lung cancer is by far the most noticeable cancer caused by
smoking with about 850,000 or 71 percent of all lung cancer
deaths caused by smoking. The next important cancers in terms
of number of deaths caused by smoking are the cancers of the
upper aerodigestive tract (mouth, oropharynx, and esophagus).

These estimates of smoking-attributable cancer mortality
"provide an important baseline" for evaluating how tobacco
control programs may contribute to reducing the global and
regional burden of cancers, the investigators conclude.

SOURCE: International Journal of Cancer, October 10, 2005.