Cigarette smoking appears to increase the risk of developing leukemia, and kicking the habit may not be enough to dodge the dreaded blood disease, a study says.

Paul K. Mills, a professor at Loma Linda University and the principal author of the study, said research suggests that even former smokers are at high risk."It's very discouraging," Mills said Monday. "We saw a strong association between prior cigarette smoking and the risk of developing leukemia."

The study's results are being published this month in the Journal of the National Cancer Institute.

Cigarette smoking also has been linked to cancers of the lung, bladder, pancreas, esophagus, throat and cervix.

The study is part of the Adventist Health Study, a major epidemiological investigation of the causes of various cancers among California members of the Seventh-day Adventist Church. About 34,000 Adventists responded to the study.

Although the vast majority of Adventists do not smoke by church proscription, many are adult converts who smoked cigarettes prior to their baptism into the church.

The researchers found that the ex-smokers had twice the risk of developing leukemia than non-smokers.

For people who regularly smoked more than 25 cigarettes a day, the risk of developing leukemia increased threefold.