The International Association for the Study of Lung Cancer (IASLC) reports that in the U.S., the National Lung Cancer Screening Trial (NLST) demonstrated that annual screening of high-risk individuals with LDCT for early indications of lung cancer can reduce lung cancer mortality by 20 percent and overall mortality by seven percent.

The National Cancer Institute notes that the NLST investigators compared two modalities for of detecting lung cancer: low-dose helical computed tomography (CT) — often referred to as spiral CT — and standard chest X-rays. Helical CT uses X-rays to obtain a multiple-image scan of the entire chest, while a standard chest X-ray produces a single image of the whole chest with anatomic structures overlying one another.

The NLST study findings showed that participants receiving low-dose helical CT scans had a 15 to 20 percent lower risk of lung cancer mortality than did participants who received standard chest X-rays — equivalent to approximately three fewer deaths per 1,000 people screened in the CT group compared to the chest X-ray group over a period of about seven years of observation (17.6 per 1,000 versus 20.7 per 1,000, respectively).

The NLST study reported that on average over the three rounds of screening exams, 24.2 percent of the low-dose helical CT screens were positive and 6.9 percent of chest X-rays were positive. In both arms of the trial, the majority of positive screens led to additional tests.

The IASLC — the only global organization dedicated to the study of lung cancer — in a release written by IASLC Scientific Projects Manager Murry W. Wynes, PhD., notes that there are currently multiple lung cancer screening trials ongoing globally, but says concern has been raised regarding is the high number of early repeat scans for suspicious findings that are in fact not lung cancer. This high number of false positives could make screening impractical due to cost, invasive follow-up procedures, and anxiety for the patients.

For instance, researchers conducting the German Lung Cancer Screening Intervention Trial (LUSI) — one of several European randomized trials investigating the efficacy of low-dose multislice CT (MSCT) — as a screening tool for lung cancer, report that they’ve observed exceptionally high early recall rates which render routine application of MSCT screening questionable. Study data reportedly show that the early repeat scan rate for suspicious findings decreased by more than 80 percent with second and subsequent low-dose computed tomography (LDCT) screens, and the scientists point to a need for an organized screening program with the baseline scan available for comparison.

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The LUSI investigators compared no intervention (n=2023) to five annual screens of individuals’ aged 50-69 with a history of heavy tobacco smoking (n=2029). All participants had been followed for at least three years, and many of them for five years. The control arm is tracked with an annual questionnaire and query of cancer registries. The LUSI is currently ongoing but data derived from current interim analyses compare the first screening round to subsequent rounds with respect to performance indicators and basic characteristics of screening, e.g. early recall rate, detection rate, interval cancers as well of proportion of advanced cancers descriptively evaluated and, if deemed informative, group differences tested for statistical significance.

Results e-published ahead of print this week by the Journal of Thoracic Oncology, the official journal of the IASLC, entitled “Randomized study on early detection of lung cancer with MSCT in Germany: results of the first 3 years of follow-up after randomization“ is coauthored by N. Becker 1, E. Motsch, M.L. Gross, A. Eigentopf, C.P. Heussel, H. Dienemann, P.A. Schnabel, M. Eichinger, D.E. Optazaite, M. Puderbach, M. Wielpütz, H.U. Kauczor, J. Tremper, and S. Delorme of the German Cancer Research Center Divisions of Cancer Epidemiology Department of Radiology, and Thoraxklinik Heidelberg; and the University of Heidelberg Department of Radiology, Department of Surgery, Department of Diagnostic and Interventional Radiology. and Translational Lung Research Center (TLRC) at Heidelberg, Germany

The coauthors note that they observed a strong decline in the early recall rate from 20 percent in the first screening round, to 3-4 percent in rounds 2-4 (p<0.0001). Lung cancer detection was 1.1 percent in the first round but then declined to 0.5 percent on average in subsequent rounds. The IASLC reports that the cumulative number of advanced lung cancers remained virtually identical between control and intervention groups during the first two years, but by year three the number of advanced cancers in the screening group began to decline, with a similar trend observed with respect to overall mortality. Detection and biopsy rates were approximately one percent or lower, and the ratio of malignant:benign biopsies 1:1.6-1:3.

The investigators conclude that while their recent data may settle one concern regarding high recall rates in routine MSCT screening, they also indicate that screening must be strictly organized in order to be effective, and performance indicators are similar to those in mammography screening. Nevertheless, they note that possible consequences for trial participants (diagnostic workup of suspicious findings, biopsies) are more invasive than in mammography screening, and that “our data indicate that the most prominent side effect ‘false positive alarm’ cannot be controlled if the choice of doctor is at the screenee’s discretion at every annual screening visit. The early recall rates of rounds 2-4 would have been around 30 percent, instead of 3-4 percent, if the prior scans were not available. Thus, a potential lung cancer screening program must be organized such that all previous images and results are available.”

The International Association for the Study of Lung Cancer (IASLC) membership includes more than 4,000 lung cancer specialists in 80 countries. To learn more about IASLC visit:
http://www.iaslc.org

Sources:
The International Association for the Study of Lung Cancer (IASLC)
The Journal of Thoracic Oncology
The National Cancer Institute
The National Lung Screening Trial (NLST)
The German Lung Cancer Screening Intervention Trial (LUSI)