Lung Cancer Screening with CT

Abstract

Lung cancer is the leading cause of cancer death in the United States. In 2007, it is estimated that 160,390 lung cancer deaths will occur in the US, representing 29% of all cancer deaths (1). Roughly 87% of lung cancers are attributed to cigarette smoking (2). Although cancer risk is attenuated by smoking cessation, the risk is not eliminated, and lung cancer now occurs with equal frequency in current and former smokers (3). Moreover, other factors clearly influence risk, including age; family history; chronic obstructive pulmonary disease; pulmonary fibrosis; and exposures to environmental radon, asbestos, and certain other occupational agents (4). Realistically, lung cancer will likely remain at epidemic proportions for decades to come.Non-small cell lung cancer (NSCLC), which accounts for 75-80% of all lung cancers, is typically diagnosed when disease is locally advanced or there are systemic metastases (5), explaining the dismal overall five-year survival of 15% (6). In contrast, the five-year survival of individuals with surgically resected, early stage NSCLC approaches 75% (6,7). These differences have fueled the impetus to find a screening test that can detect NSCLC in its early preclinical stages, when surgical resection is most likely to prolong life and potentially reduce lung cancer mortality. Although earlier randomized controlled trials of lung cancer screening using chest radiography and sputum cytology failed to show reduced lung cancer mortality, computed tomography (CT) is a much more sensitive test for detecting small lung nodules, and has generated considerable enthusiasm as a potential contemporary screening tool for lung cancer.

Chronic inflammation, chronic obstructive pulmonary disease, and lung cancer

“…Although the majority of patients who developed lung cancer had airway obstruction and emphysema, a small proportion had emphysema alone. Finally, previous CT screening studies have not yet reported on the impact of radiographically detected emphysema in lung cancer risk [48].…”

Screening and Biosensor-Based Approaches for Lung Cancer Detection

“…These techniques have some drawbacks, such as being expensive and having low sensitivity for identifying cancer cells at early stages. Annual CRG was reported as not helpful in reducing the mortality of lung cancer [ 16 ]. CT has been considered as the gold standard lung screening tool, which offers information of tumor features such as size, characterization and tumor growth.…”

In Reply

“…Bach is correct that the references we cited to support the statement that the median length of follow-up for the National Lung Screening Trial (NLST) is 4 years do not directly provide this information. The follow-up time for the NLST is 4 -6 years, as was recently confirmed by the principal investigator of the NLST [7], not the 5-7 years as stated by Bach. We estimated that the median follow-up time would be further shortened and closer to 4 years, because the NLST protocol [8] calls for information regarding cause of death to be obtained from the National Death Index, which is usually not available until one and a half years after the death has occurred.…”