CT detects twice as many lung cancers as X-ray

PHYSICIANS have more information to share with their patients about the benefits and risks of LDCT lung cancer screening following the publication in the New England Journal of Medicine of the results of the first (of three planned) annual screening examinations from the National Lung Screening Trial (NLST).

NLST investigators also conclude that the 20%reduction in lung cancer mortality with low-dose computed tomography (LDCT) versus chest X-ray (CXR) screening previously reported in the NLST primary paper is achievable at experienced screening centers in the United States.

“For a cancer screening to work, it’s important to verify that it can in fact discover cancers early. The analysis of NLST participants’ initial annual screening examination provides evidence that the number of early-stage cancers detected in the trial’s CT arm were significantly greater than the number detected in the chest X-ray arm,” said Timothy Church, Ph.D., a biostatistician and professor in the School of Public Health at the University of Minnesota who has been involved with the NLST’s design, implementation and analysis.

Professor Church also points out that a reduction in mortality is the ultimate indicator of a successful cancer screening strategy. The NLST is a large-scale, longitudinal clinical trial that randomized over 53,400 study participants equally into either the LDCT or standard CXR arm to evaluate whether lung cancer screening saves lives. Published results (NEJM; 2011) reported a 20% reduction in lung cancer deaths among study participants (all at high risk for the disease) screened with LDCT versus those screened with CXR.

The authors report that the NLST initial-screening results are reflective of other large trials with regard to positive LDCT versus CXR results, with more positive screening exams [7191 vs. 2387, respectively], more diagnostic procedures [6369 vs. 2176, respectively], more biopsies and other invasive procedures [297 vs. 121, respectively], and more lung cancers seen in the LDCT arm than in the CXR arm during the first screening round of NLST [292 vs. 190, respectively]. Although these results were generally anticipated, a key reason to publish the data was to document the exact differences between the two arms.

“Although we did see that CT resulted in referring more patients for additional testing, the question comes down to whether the 20% reduction in mortality is worth the additional morbidity introduced by screening high-risk patients,” said Professor Church. He notes that although there were more follow-up procedures in the LDCT versus the CXR arm, it was encouraging to confirm that the number of individuals who actually had a more invasive follow-up procedure was quite small.

Another encouraging result reported is the high rate of compliance in performing the LDCT examination as specified in the research protocol across the 33 imaging facilities that carried out the study.

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