New data inflame debate over lung cancer screening

July 1, 2007

Considering that lung cancer accounts for the largest chunk by far of estimated deaths relative to other cancer sites for both men and women in the U.S., the high level of interest in early detection techniques among consumers and doctors is not surprising. CT screening appears to be the most likely candidate for arresting lung cancers, but its value and use remain controversial.

Considering that lung cancer accounts for the largest chunk by far of estimated deaths relative to other cancer sites for both men and women in the U.S., the high level of interest in early detection techniques among consumers and doctors is not surprising. CT screening appears to be the most likely candidate for arresting lung cancers, but its value and use remain controversial.

In a major high-profile release just prior to the 2006 RSNA meeting, researchers with the International Early Lung Cancer Action Program (I-ELCAP) showed that 85% of cancers picked up with low-dose CT were found at stage I. They estimated that patients who underwent resection had a 93% 10-year survival rate, and concluded that CT screening could prevent 80% of lung cancer deaths (NEJM 2006;355;17:1763-1771).

Subsequently, letters to the editor and opinion columns flowed like wine, with many authors questioning the effect of lead time bias on the I-ELCAP results and expressing concern about ethics, considerable risks associated with surgery on screen-detected findings, and potentially detrimental effects on healthcare resources.

The New York arm of the ELCAP group published another study in April, showing that screening helps catch lung cancers in their early stages (Radiology 2007;243;1:239-249).

Researchers at three institutions, however, including the Mayo Clinic, found that CT may not reduce mortality rates (JAMA 2007;297;9:953-961). Using a computer modeling technique, they concluded that early detection with CT did not cut the number of advanced lung cancer diagnoses or lower the actual death rate compared with expectations absent screening. Screening results in three times the number of lung cancer diagnoses and 10 times the number of resections, according to this paper.

Researchers at Queens College in New York City have suggested protocols for following indeterminate nodules based on results from a study of 4000 screening patients in Queens (Chest 2007;131:1028-1034).

"The problem of false-positive CT scans and related anxiety in early lung cancer screening programs has been a major concern among some scientists in the field. This study puts a real number on the likelihood that an indeterminate nodule is actually a cancer and also allows physicians to inform patients about this low likelihood," said lead author Dr. Steven Markowitz, director of the Center for the Biology of Natural Systems at Queens College.