(RxWiki News) Finding lung cancer at its earliest stages, when there is still the chance of a cure, is a problem. Regular CT scans can detect such cancers in older smokers who’ve smoked the equivalent of a pack a day for 30 years.
But even in this ‘high risk’ group, the cost of finding each cancer can be prohibitive because of all the people who don’t have cancer who have to be screened. Having a better way to assess lung cancer risk is urgently needed.
Scientists have found that male smokers with lower levels of bilirubin in the blood are at higher risk of developing and dying from lung cancer than men with higher bilirubin levels.
Bilirubin is a reddish-yellow tint that’s formed in the liver. Normally, too much of this substance, causing jaundice, is associated with the presence of disease.
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Xifeng Wu, MD, PhD, professor and chair of the Department of Epidemiology at The University of Texas MD Anderson Cancer Center in Houston, led research hunting for biomarkers (indicators of disease) for lung cancer.
After testing hundreds of metabolites – by-products of metabolism – the researchers found bilirubin to be the most promising. Bilirubin levels can be assessed with a simple blood test.
Hundreds of individual blood samples were involved in zeroing in on bilirubin. And researchers confirmed their findings working with a group of 435,985 individuals.
“Although it was expected that bilirubin may be protective against lung cancer incidence and mortality, we were somewhat surprised that the effect of bilirubin was only evident in smokers, which will have profound public health implications, given that 90 percent of lung cancers occur in smokers,” Dr. Wu said in a press release.
The metabolite bilirubin emerged as the most promising marker, and the researchers further validated this finding in the third phase, which included a large Taiwanese prospective cohort of 435,985 individuals.
Men with the lowest levels (0.68 mg/dL or less) of bilirubin had a 51 percent increased risk of developing lung cancer compared to those with the higher levels (1.12 mg/dL or more).
Looking at it another way, bilirubin levels found 7.02 cases of lung cancer for every 10,000 person years in the low levels vs. 3.73 per 10,000 in the group with higher bilirubin levels.
The researchers also found men with the lowest bilirubin levels had a 59 percent increased risk of dying from lung cancer as men with higher levels of the metabolite.
When looking only at smokers, those with the lowest levels of bilirubin had a 69 percent greater risk for lung cancer development and a 76 percent increased risk of dying from the disease compared to smokers with the highest levels of bilirubin.
“Smokers with low bilirubin levels had significantly increased risks for both lung cancer incidence and mortality. Serum bilirubin is a valuable biomarker for lung cancer risk prediction in ever-smokers,” the authors concluded.
dailyRx News spoke with lung cancer expert, Ross Camidge, MD, PhD, the director of the lung cancer clinical program at the University of Colorado Hospital in Aurora, about this research.
“We already know that low dose spiral CT scans can pick up some early stage lung cancers. In the high risk group in the National Lung Screening Trial (NLST), the lung cancer incidence was 645 per 100,000 person years (or 64.5 per 10,000 person years),” said Dr. Camidge, who was not involved in this research.
“Here the ‘high-risk’ group based on bilirubin seems to have a risk of lung cancer only a tenth of that in the NLST. What would be interesting would be to see if the bilirubin data can produce the same percentile change (51 percent increase in risk) in the high risk group assessed in the NLST, i.e., pushing the incidence in the screened population up to close to 100 cases per 10,000 patient-years. If it can, then this could act as a means to make CT screening more economically feasible. If it can’t then, it is unlikely that these results will alter clinical screening strategies for lung cancer,” Dr. Camidge said.
Findings from this research were presented at the American Association for Cancer Research (AACR) Annual Meeting 2013. All research is considered preliminary before it is published in a peer-reviewed journal. No conflicts of interest were declared.
