CT-based lung cancer screening can find the disease early enough to improve survival rates, especially in those patients who elect to have immediate surgery, according to the latest results from the International Early Lung Cancer Action Project (I-ELCAP).
The overall survival rate ranges from 76%-78% if the screening of asymptomatic patients turns up any lung cancers, said lead researcher Dr. Claudia Henschke, professor of radiology at New York Hospital-Cornell Medical Center in New York City.
"We found that 80% of the lung cancers are stage I lesions, which have no lymph node metastases," Henschke said during a presentation last week at the 2004 RSNA meeting in Chicago.
Started in 1993, I-ELCAP is a worldwide screening project in which 27,701 CT scans have been performed, with 19,371 follow-up examinations.
If a patient had a cancerous lesion and elected to have it excised, then 80% of those lesions turned out to be stage I, and the eight-year survival was 95%. If a patient was found to have a stage I lesion on a repeat scan, the survival rate increased to 98%.
"The survival is better in those patients because the lesions we see on the repeat CT scans are generally smaller," Henschke said.
The ELCAP database has allowed the researchers to calculate the risk of cancer, depending on the two major variables in the study, patient age and the number of pack years of cigarettes smoked. For example, about two out of 1,000 people who are 45 years of age and have smoked fewer that 30 packs per year in his or her lifetime is more likely to develop lung cancer. That risk rises dramatically if a 45-year-old has already smoked the equivalent of 60 pack years. About 10 in 1,000 people who meet that criterion will develop lung cancer, the data show.
About 170,000 new cases of lung cancer are diagnosed each year in the U.S., and about 160,000 people die each year of the disease. The five-year survival rate for lung cancer detected by doctors without screening is about 5%-10%, at which point the cancer has metastasized and the patient is symptomatic.
Henschke said data from I-ELCAP confirm previous reports about the latent lung cancer risk associated with smoking. She explained that cancer risk does not immediately decline when a current smoker stops.
"It takes at least 20 years for the risk to decrease -- up until 19 years after smokers quit, the risk stays steady and then it drops by half at 20 years," she said. She added that even when the risk drops, "former smokers always have a higher lifetime risk of lung cancer than never smokers."
Responding to critics who say screening programs result in unnecessary follow-up procedures, including biopsies, Henschke said that only "12% of first-time CT screenings require follow-up care, and on repeat screenings only 6% of patients require follow-up care. She added that when a suspicious lesion is identified on first exam, "repeat CT at one month indicates that half of these lesions go away."
Commenting on the study was Dr. Michael Brant-Zawadski, medical director of radiology at Hoag Memorial Hospital in New Port Beach, CA, and a former smoker. He said was surprised that it took so long for the lung cancer risk to decrease.
"But I think that the value of CT for lung cancer screening is fairly clear. Women are having regular mammograms, but it may be that a large population will need annual 'lungograms,'" he said.
Without consensus guidelines on screening, Henschke said undergoing screening is an individual decision, especially given the $300 out-of-pocket expense for the scan. Very few insurance payors now pay for CT lung cancer screening in certain patients.
By Edward Susman
AuntMinnie.com contributing writer
December 6, 2004
Related Reading
Web site promotes lung cancer awareness among women, November 9, 2004
CAD gets role in new ELCAP lung study, April 29, 2004
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