High-risk individuals who have lung cancer detected by low-dose spiral CT screening have longer survival than people with clinically detected lung cancer, and two large, randomized studies are seeking to determine whether such screening also reduces lung cancer mortality. But will one trial provide more conclusive evidence than the other? Is the US study, the National Lung Screening Trial (NLST), inferior to the European study known as NELSON, as some critics have claimed? Not in the view of lead researchers involved in both studies. They regard the trials as complementary, not competitive.

"Although it is interesting to compare the two trials, you should realize that a comparison in terms of superiority/inferiority is probably inappropriate," NELSON principal investigator Rob J. van Klaveren, MD, PhD, of Erasmus Medical Center, Rotterdam, told ONI. "The two studies have different designs and different approaches. They are, in a sense, complementary."

In a separate interview, NLST co-director Denise R. Aberle, MD, of UCLA, called the NELSON trial extremely important. "When our data are mature," she said, "we will be able to consider methods of doing statistical meta-analysis. Our patient cohorts are close enough that we will gain information and, in effect, validation from the NELSON trial because it was done by an independent group."

NLST critics consist largely of advocates for low-dose CT screening who are convinced that earlier I-ELCAP reports showing increased survival (N Engl J Med 355:1763-1771, 2006) are adequate to support its use in examining high-risk individuals for early lung cancer.

"There are groups that go to state legislatures to try to get money from the Tobacco Settlement funds apportioned to researchers who are pro screening and to the US Congress to get legislation introduced to mandate Medicare coverage for screening," said Peter Bach, MD, of Memorial Sloan-Kettering Cancer Center, who is not involved in NLST.

These same individuals and groups appear to be trying to find flaws in the NLST, he said, perhaps because they fear the results.

"The research community regards a randomized trial of screening to be the gold standard, and there is a legitimate chance that NLST may show that CT is not beneficial," Dr. Bach said.

The study protocols