MONDAY, Jan. 14 (HealthDay News) -- Heavy smokers are more likely to develop aggressive and deadly bladder cancers than those who smoke less or nonsmokers, new research shows.

Smoking is one of the most common causes of bladder cancer, but it hasn't been known how it affects the progress of the disease.

In this study, researchers looked at data from 212 bladder cancer patients in Los Angeles County, in California. Patients who were heavier smokers were more likely to have deadly bladder cancer than those who were lighter smokers or those who never smoked.

The study also identified changes in certain proteins that are often present in lethal bladder cancer. Patients with changes in six to nine proteins fared badly, which suggests that they could have benefited from more aggressive treatment.

The greater the number of changes in these proteins, the worse a patient's outcome, according to the study published online Jan. 14 in the journal Cancer.

Although the study tied heavier smoking to higher death risk from bladder cancer, it did not establish a cause-and-effect relationship.

The findings are important because bladder cancer is one of the most expensive types of cancer to treat, study co-author Dr. Richard Cote, of the University of Miami Miller School of Medicine, said in a journal news release.

He said treatment tailored to individual bladder cancer patients is "urgently needed."

More information

The U.S. National Cancer Institute has more about bladder cancer.