RSNA News - March 2005

CT Screenings Predict Smoker's Lung Cancer Risk

This is the first time we are reporting our prognostic mission for estimated cure rates of screen-diagnosed resected lung cancers without lymph node metastasis in this pool cohort.
—Claudia I. Henschke, Ph.D., M.D.

Researchers can now predict a smoker's chance for developing lung cancer based on age, how much has been smoked and when the smoker quit.

Claudia I. Henschke, M.D., Ph.D.

New York Hospital/Cornell Medical Center

The International Early Lung Cancer Action Project (I-ELCAP) is the largest study of its kind showing annual CT screenings can identify a high percentage of Stage I lung cancer in habitual and social smokers.

"The mission of the research is to advance policy-relevant research on early diagnosis of lung cancer," explained principal investigator Claudia I. Henschke, Ph.D., M.D., during a scientific paper session at RSNA 2004. "Data were pooled across 33 international institutions using the same regimen of screening. Since 1993, 27,701 men and women have undergone CT screenings to evaluate the usefulness of CT as a diagnostic tool and to foster translation of up-to-date evidence for guidelines for practice."

Annual CT screenings have been shown to identify a high percentage of Stage I diagnoses of lung cancer in its most curable form. "Our study found that deaths from Stage I lung cancer were surprisingly low after surgery, but only if treatment is pursued quickly," said Dr. Henschke, a professor of radiology and division chief of chest imaging at New York Hospital/Cornell Medical Center in New York City.

Calling the study a diagnostic-prognostic trial in which everyone is screened initially, she added, "This is the first time we are reporting our prognostic mission for estimated cure rates of screen-diagnosed resected lung cancers without lymph node metastasis in this pool cohort."

The results showed less than 15 percent had a positive result for lung cancer in the initial or baseline screening. Less than six percent required further work-up following the annual repeat screening. Of those with a positive screening in either baseline or repeat, more than 80 percent were diagnosed in Stage I.

When it comes to translating the research into guidelines for practice, Dr. Henschke said it is important to treat each case individually. "When you are meeting a patient who wants to be screened, you can answer his or her questions based on the likelihood of finding cancer in that round of screening, the likelihood that early intervention would cure the cancer and the likelihood of avoiding death by another cause," she said.

I-ELCAP showed for those between 40 and 49, for every 1,000 people screened, you will find two cases of lung cancer averaged over all pack years. The number of cases increased to 15 for every 1,000 for people aged 50 to 74 years and 28 out of every 1,000 for those over 75.

The number of smokers developing lung cancer also increased by the total number of cigarettes smoked: 28 smokers out of every 1,000 were diagnosed with lung cancer if they smoked three packs a day for 20 years or more. Fifteen smokers per 1,000 developed lung cancer among those smoking three packs a day for 10 to 20 years.

Lung cancer remains the major cause of cancer death in women and men, killing more people than breast, prostate and colon cancers combined, according to the American Cancer Society.

Future of I-ELCAP

Dr. Henschke said I-ELCAP researchers will continue to update the regimen of screening in accordance with advances in knowledge and technology. They will follow the screen-diagnosed cases of lung cancer to establish the fatality rate with and without early intervention. They will also develop guidelines for post-primary lung cancer screening and participate in the assessment of alternative treatments for early screen-diagnosed lung cancers.

This story was adapted from an article that appeared in the RSNA 2004 Daily Bulletin.