Screening chest x-ray detects a substantial number of lung cancers at an early potentially curable stage, according to initial findings from the largest US study of the efficacy of screening for lung cancer in men and women.

According to the initial chest x-rays of 77,465 people in the screening arm of the trial, 5,991 - nearly 9 percent - had results that were deemed “suspicious for lung cancer.”

Upon further testing, 126 individuals were diagnosed with lung cancer and, importantly, say the investigators, 44 percent of the tumors were early localized stage I cancers.

“This is a tantalizing first step, raising the possibility of real benefit,” Dr. Martin M. Oken, of the Hubert H. Humphrey Cancer Center, Robbinsdale, Minnesota told Reuters Health.

“Screening,” he pointed out, “is predicated on the assumption that it can lead to discovery of dangerous cancers at an earlier, more localized stage when it is more likely to be curable. In the current study, nearly 50 percent of screen-detected lung cancer is localized.”

Historically, in unscreened populations, only 15 percent to 20 percent of lung cancers are diagnosed while localized.

Worldwide, one million people die from lung cancer each year. When lung cancer first develops, there may be no symptoms at all. When a patient starts to experience symptoms, such as a cough that doesn’t go away, the cancer is often advanced and treatment is rarely effective.

In the current study, high rates of lung cancers were found in current smokers and in former smokers (6.3 and 4.9 per 1000 screens). Among never smokers, the lung cancer detection rate was 0.4 per 1000 screens. This group accounted for 11 percent of the cancer identified.

The final analysis of the study, Oken said, will compare the findings in these 77,465 screened individuals, which are reported in today’s Journal of the National Cancer Institute, with a like number of unscreened subjects to determine whether screening can reduce death from lung cancer.

“As little as a 20 percent mortality reduction associated with screening,” he concluded, “could save 32,000 lives annually in the US alone.”

SOURCE: Journal of the National Cancer Institute, December 21, 2005.