There appears to be an association between reduced lung function and the risk of lung cancer, Canadian researchers report.

Dr. D. D. Sin said, “Even relatively small reductions in lung function, which are considered within the normal range, increased the risk of lung cancer by 30 percent to 60 percent, especially among women.”

Sin and colleagues from the University of British Columbia, Vancouver, reviewed existing studies that have looked into the relationship between lung function and the risk of lung cancer. The analysis involved 204,990 subjects, of whom 6185 had died from lung cancer.

As lung function decreased, the risk of lung cancer increased, the team reports in the issue of Thorax.

Compared to men with the highest levels of forced expiratory volume in 1 second (called FEV1), those with the lowest had a more than 2-fold increased risk of lung cancer.

Women with the lowest FEV1 had a nearly 4-fold increased risk compared to those with the highest.

The investigators say that inflammation of the lungs and airways caused by cigarette smoke and other noxious irritants is a possible explanation for the relationship between reduced lung function and an increased lung cancer risk.

Or it may be that people with reduced FEV1 may have an impaired ability to clear inhaled cancer-causing substances from their airways.

“Since lung cancer can occur in individuals with only small decreases in FEV1, especially in women,” concluded Sin, “the traditional boundaries of normal FEV1 may need to be modified for screening purposes.”

SOURCE: Thorax, July 2005.