Study questions ability of CT screening to reduce lung cancer deaths

March 7, 2007

An eight-year international study of more than 3000 current and former smokers has found that screening CT leads to early lung cancer diagnosis but does not cut lung cancer death rates for people who receive annual screening.

An eight-year international study of more than 3000 current and former smokers has found that screening CT leads to early lung cancer diagnosis but does not cut lung cancer death rates for people who receive annual screening.

Although CT screening found nearly three times as many lung cancers as predicted, lead author Dr. Peter Bach, a pulmonologist/intensivist at Memorial Sloan-Kettering Cancer Center in New York City, found that early detection and treatment did not lead to a corresponding decrease in advanced lung cancers or a reduction in deaths from lung cancer.

The multicenter study found no advantage to using CT screening on current or former smokers, the population at highest risk for developing lung cancer. The findings appear in the March 7 issue of the Journal of the American Medical Association.

"Ours is the first study to ask whether detecting very small growths in the lung by CT is the same as intercepting cancers before they spread and become incurable. We found an answer, and it was no," Bach said. "Early detection and additional treatment did not save lives but did subject patients to invasive and possibly unnecessary treatments."

Beginning in 1998, 3246 asymptomatic men and women with a median age of 60 who had smoked or still smoked for an average of 39 years were screened for lung cancer with multislice CT at the Mayo Clinic in Rochester, MN, the H. Lee Moffitt Cancer Center & Research Institute in Tampa, or Instituto Tumori in Milan. Subjects received an initial CT scan and then at least three subsequent annual exams.

Annual screening found more than three times as many lung cancers as the number that would have been diagnosed without screening. Ten times as many surgeries were performed for lung cancer compared with what was expected, according to the study. This meant that as a direct result of the test, an additional 99 people were diagnosed with lung cancer and an additional 98 had lung surgery. The early detection and treatment did not change the death rate, however. There were 38 deaths due to lung cancer, and 39 would have occurred without screening.

The results differ from findings published by The New England Journal of Medicine in October (NEJM 2006;355[17]:1763-1771). Data compiled from the International Early Lung Cancer Action Program (I-ELCAP) led by Dr. Claudia I. Henschke, a professor of radiology and cardiothoracic surgery at Weill Medical College of Cornell University, found that 80% of people whose lung cancer is caught early with CT screening can expect to live at least another decade.

The JAMA study generated no evidence that CT screening prevented deaths from lung cancer, according to senior author Colin Begg, Ph.D, chair of epidemiology and biostatistics department at Memorial Sloan-Kettering.

"With lung cancer the number one cause of cancer deaths in the U.S., the medical profession continues to seek an effective and safe approach to prevent deaths from this disease. According to our study, CT screening may not be it," he said.

Ethicists sound off about lung cancer CT screening

CT screening for lung cancer stirs safety, ethics concerns

Lung CT screening saves at-risk lives