Frequent Lung Cancer Screening Benefit Goes Up in Smoke
Aug. 15, 2000 -- Smokers who think they can cheat death by having regular lung cancer screenings are dead wrong, according to results of the 20 year Mayo Lung Project. In fact, the researchers tell WebMD, male smokers who underwent intense screening were somewhat more likely to die from lung cancer than those who went for the more standard, yearly exams.
The findings tell us two important things, study leader Pamela M. Marcus, MS, PhD, tells WebMD: First, that there is no reduction in lung cancer deaths with increased screening, and second, that increased screening picks up tumors that aren't likely to cause serious problems. Marcus is an epidemiologist in the division of cancer prevention at the National Cancer Institute in Bethesda, Md.
Originally conducted between 1971 and 1983, the trial compared the death rate from lung cancer in more than 9,000 male smokers who received either intense or standard lung cancer screening. Those in one group had a chest X-ray and sputum analysis every four months for six years. Another group got a single recommendation at the start of the study to have the same screening once a year.
When the study ended, the researchers reported their controversial findings: Although the men in the frequent screening group survived longer with cancer, there was no difference in the number of deaths from cancer between the two groups.
These findings came as a complete surprise when they were published in the early '80s, William C. Black, MD, tells WebMD. Black, a professor of radiology at Dartmouth-Hitchcock Medical Center in Lebanon, N.H., wrote an editorial accompanying the study. Since X-rays can pick up very small cancers, people had estimated that intense screening would reduce lung cancer deaths by 50%, he says.
But as it turns out, even though the screening did detect more cancers, and at a much earlier stage, and "patients did seem to be living longer from the time of their diagnosis, there was no difference in the number of deaths caused by lung cancer in the two groups," says Black. "It was a paradox."
The unexpected outcome led to a host of criticisms of the trial, with fingers pointing to the study design, the methods used, and the analysis. Critics argued that the researchers hadn't followed the men for long enough to see a benefit. Now, says Black, this very long-term follow-up of that study goes a long way toward clearing up the confusion.
By consulting the National Death Index, the team was able to assess the time and cause of death for more than 6,500 of the study participants. Even 20 years after the study, there was still "no significant decrease in lung cancer death with intense screening," says Black.