If current trends hold, tobacco will kill a billion people this century, 10 times the toll it took in the 20th century, public health officials said Monday.

Tobacco accounts for one in five cancer deaths, or 1.4 million deaths worldwide each year, according to two new reference guides that chart global tobacco use and cancer. Lung cancer remains the major cancer among the 10.9 million new cases of cancer diagnosed each year, according to the Cancer Atlas.

Reducing tobacco use would have the greatest affect on global cancer rates, health officials said. Improving nutrition and reducing infection by cancer-causing viruses and bacteria could also cut rates dramatically, they said.

"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.

The new Cancer Atlas and updated Tobacco Atlas were released Monday at a International Union Against Cancer conference. The American Cancer Society published the two atlases with help from the Union, WHO and Centers for Disease Control and Prevention.

"Even if smoking rates decline worldwide, there will be a constant or even slightly increasing number of smokers due to population increases," said Michael Eriksen, director of the Institute of Public Health at Georgia State University.

An estimated 1.25 billion men and women smoke cigarettes now, according to the Tobacco Atlas.