A review of large, population-based, prospective studies that adjusted for smoking history shows that even moderate decreases in forced expiratory volume (one second) are associated with increased risk for lung cancer, according to an article in the July issue of Thorax.

The analysis included 204,990 participants, of whom 6,185 had been diagnosed with or died from lung cancer. The average age of participants ranged from 42 to 47 years and follow up time was 9 to18 years.

Compared with the best lung function measurements, men with the worst lung function had more than twice the risk of lung cancer, and women had nearly four times the risk. 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. Other smaller studies, not included in this analysis, showed similar results.

Independent of cigarette smoking history, reduced FEV1 increases the risk for lung cancer in the general population, the authors concluded.
Possible explanations for this relationship include lung and airway inflammation caused by cigarette smoke and other noxious irritants. Alternatively, individuals who have reduced FEV1 may have an impaired ability to clear inhaled carcinogens from their airways.

Despite some limitations, the authors believe that these findings are a step forward in helping doctors to uncover the disease at an earlier stage. Furthermore, because lung cancer can occur in individuals with only small decreases in FEV1 (especially in women), the traditional boundaries of “normal” FEV1 may need to be modified for screening purposes, they conclude.