Interval lung cancers not detected on screening chest X-rays: How are they different?

BACKGROUND: The Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial provides us an opportunity to describe interval lung cancers not detected by screening chest X-ray (CXR) compared to screen-detected cancers. METHODS: Participants were screened for lung cancer with CXR at baseline and annually for two (never smokers) or three (ever smokers) more years. Screen-detected cancers were those with a positive CXR and diagnosed within 12 months. Putative interval cancers were those with a negative CXR screen but with a diagnosis of lung cancer within 12 months. Potential interval cancers were re-reviewed to determine whether lung cancer was missed and probably present during the initial interpretation or whether the lesion was a "true interval" cancer. RESULTS: 77,445 participants were randomized to the intervention arm with 70,633 screened. Of 5227 positive screens from any screening round, 299 resulted in screen-detected lung cancers; 151 had potential interval cancers with 127 CXR available for re-review. Cancer was probably present in 45/127 (35.4%) at time of screening; 82 (64.6%) were "true interval" cancers. Compared to screen-detected cancers, true interval cancers were more common among males, persons with <12 years education and those with a history of smoking. True interval lung cancers were more often small cell, 28.1% vs. 7.4%, and less often adenocarcinoma, 25.6% vs. 56.2% (p<0.001), more advanced stage IV (30.5% vs. 16.6%, p<0.02), and less likely to be in the right upper lobe, 17.1% vs. 36.1% (p<0.02). CONCLUSION: True interval lung cancers differ from CXR-screen-detected cancers with regard to demographic variables, stage, cell type and location. ClinicalTrials.gov number: NCT00002540.

The National Lung Screening Trial: overview and study design.

The National Lung Screening Trial (NLST) is a randomized multicenter study comparing low-dose helical computed tomography (CT) with chest radiography in the screening of older current and former heavy smokers for early detection of lung cancer, which is the leading cause of cancer-related death in the United States. Five-year survival rates approach 70% with surgical resection of stage IA disease; however, more than 75% of individuals have incurable locally advanced or metastatic disease, the latter having a 5-year survival of less than 5%. It is plausible that treatment should be more effective and the likelihood of death decreased if asymptomatic lung cancer is detected through screening early enough in its preclinical phase. For these reasons, there is intense interest and intuitive appeal in lung cancer screening with low-dose CT. The use of survival as the determinant of screening effectiveness is, however, confounded by the well-described biases of lead time, length, and overdiagnosis. Despite previous attempts, no test has been shown to reduce lung cancer mortality, an endpoint that circumvents screening biases and provides a definitive measure of benefit when assessed in a randomized controlled trial that enables comparison of mortality rates between screened individuals and a control group that does not undergo the screening intervention of interest. The NLST is such a trial. The rationale for and design of the NLST are presented.

Final results of the Lung Screening Study, a randomized feasibility study of spiral CT versus chest X-ray screening for lung cancer.

The Lung Screening Study (LSS) was a pilot study designed to assess the feasibility of conducting a large scale randomized controlled trial (RCT) of low radiation dose spiral computed tomography (LDCT) versus chest X-ray (CXR) for lung cancer screening. Baseline results of LSS have been previously reported. Here, we report on the findings at the year one screen and on the final results of the LSS study. A total of 1660 subjects were randomized to the LDCT arm and 1658 to the CXR arm. Compliance with screening declined from 96% at baseline to 86% at year one in the LDCT arm and declined from 93% at baseline to 80% at year one in the CXR arm. Positivity rates for the year one screen were 25.8% for LDCT and 8.7% for CXR. Cancer yield was significantly less at year one for LDCT, 0.57%, than at baseline, 1.9%; cancer yield for CXR increased from 0.45% at baseline to 0.68% at year one. Forty lung cancers in the LDCT arm and 20 in the CXR arm were diagnosed over the study period. Stage I cancers comprised 48% of cases in the LDCT arm and 40% in the CXR arm. A total of 16 stage III-IV cancers were observed in the LDCT arm versus nine in the CXR arm. The LSS has established the feasibility of a RCT comparing annual spiral CT to chest X-ray for lung cancer screening.

Developmental lung anomalies in the adult: radiologic-pathologic correlation.

Encountering a developmental lung anomaly in the adult can be a challenge, as the abnormality may be mistaken for something more sinister. The common anomalies encountered are classified into three broad categories: bronchopulmonary (lung bud) anomalies, vascular anomalies, and combined lung and vascular anomalies. The imaging features of these developmental anomalies at conventional radiography, ventilation-perfusion lung nuclear scanning, angiography, computed tomography, and magnetic resonance imaging are useful in differential diagnosis of thoracic lesions. Lung bud anomalies include agenesis, congenital bronchial atresia, congenital lobar emphysema, congenital cystic adenomatoid malformation, pulmonary bronchogenic cysts, tracheal or pig bronchus, and accessory cardiac bronchus. Vascular anomalies include interruption or absence of a main pulmonary artery, anomalous origin of the left pulmonary artery from the right, anomalous pulmonary venous drainage (partial or complete), and pulmonary arteriovenous malformation. Combined lung and vascular anomalies include the hypogenetic lung (scimitar) syndrome and bronchopulmonary sequestration, both intralobar and extralobar.