Old Biomarker May Have New Role in Lung Ca

Bilirubin, which is considered a useful liver function marker, may also point to smokers at increased risk for lung cancer.

In a large Taiwanese prospective cohort, male smokers with bilirubin in the lowest quartile lowest had a 69% higher risk for developing lung cancer, and a 76% higher rate of lung cancer mortality, compared with male smokers who had the highest bilirubin levels, said Xifeng Wu, MD, of the University of Texas MD Anderson Cancer Center in Houston.

In men who had never smoked, bilirubin levels had no significant effect on health outcomes.

The research showed that serum bilirubin is a potential biomarker for lung cancer risk prediction, Wu told MedPage Today at the annual meeting of the American Association for Cancer Research.

"It was kind of a surprise and very interesting," Wu said. "The biomarker was identified from metabolic profiling and validated by the large, cohort study."

In the Taiwanese cohort of 435,985 individuals, the incidence rate of lung cancer in men with bilirubin levels of 0.68 mg/dL or less was 7.02 per 10,000 person-years irrespective of smoking history. This compared with a rate of 3.73 per 10,000 person-years in men whose bilirubin levels were 1.12 mg/dL or more, again irrespective of smoking history.

Wu said this translated into a 51% increase in the risk for developing lung cancer for low-bilirubin patients.

Also, the lung-cancer specific mortality rate in men with low bilirubin was 4.84 per 10,000 person-years compared with 2.46 per 10,000 person-years in men with high bilirubin.

When only male smokers were analyzed the associations were starker -- a 76% increase in lung cancer mortality.

Wu said she first conducted global, unbiased metabolomic profiling in serum samples from 20 healthy controls, 20 patients in early-stage lung cancer, and 20 patients in late-stage lung cancer. Matching for age and gender, Wu selected three differentially expressed metabolites for validation in two case-control populations. Bilirubin emerged and was validated by the large Taiwanese prospective cohort.

Wu said the study focused on male smokers and was limited by an insufficient amount of female smokers from which to draw conclusions.

But the research does point to the potential benefit of using biomarkers in cancer research, she said.

"We need to identify additional biomarkers, including metabolomic biomarkers," Wu said.

"It's a very large study and brings up interesting findings that to my knowledge haven't been reported before," said Lecia Sequist, MD, of Massachusetts General Hospital in Boston. "This will generate a lot of interesting future research in biologic relations between bilirubin and lung cancer."

Tomado de  medpagetoday.com