WASHINGTON – Curbing tobacco use and taking other steps to eliminate some of the most common risk factors for cancer could save millions of lives over the next few decades, health officials said Monday.

Tobacco alone is predicted to kill a billion people this century, 10 times the toll it took in the 20th century, if current trends hold.

Reducing tobacco use would have the single largest effect on global cancer rates, John Seffrin, chief executive officer of the American Cancer Society, and other health officials said Monday in unveiling two reference guides that chart global tobacco use and cancer.

“We know with cancer, if we take action now, we can save 2 million lives a year by 2020 and 6.5 million by 2040,” said Dr. Judith Mackay, a World Health Organization senior policy adviser.

Today, tobacco accounts for one in five cancer deaths, or 1.4 million deaths worldwide each year, according to the new Cancer Atlas.

When deaths from tobacco-related cardiovascular and pulmonary diseases are included, the yearly death toll rises to nearly 5 million and it’s expected to keep going up.

An estimated 1.25 billion men and women currently smoke cigarettes, and more than half of them will die from the habit, according to the newly issued second edition of the Tobacco Atlas.

Lung cancer remains the major illness among the 10.9 million new cases of cancer diagnosed each year, according to the Cancer Atlas.

In 2002, besides the nearly 11 million new cancer cases worldwide, there were nearly 7 million cancer deaths. By 2020, officials anticipate there will be 16 million new cancer cases a year and 10 million deaths.