Lung cancer screening: current status

Abstract

Lung cancer remains the leading cause of death from malignancy with approximately 1.3 million deaths occurring world wide per year [1]. Approximately 70 % of cases have incurable disease at presentation which is either widely metastatic or locally advanced [1]. The overall 5-year survival still remains very low at only 14 % [1]. Lung cancer, however, which is detected early in its course, demonstrates much better survival data. Survival in non-small-cell lung cancer Stage I is greater than 70 % and small peripheral less than 1 cm lung cancers have survival rates of greater than 80 % [2]. The rationale for screening is, therefore, obvious. Diagnosis of lung cancer early in preclinical stages has a higher cure rate and, therefore, high-risk asymptomatic individuals are likely to benefit from screening.The introduction of helical and subsequently multidetector CT in the 1990s led to a number of feasibility studies in which CT was used as a screening tool for the detection of early asymptomatic lung cancer. Observational single arm trials were conducted for several years in many countries including the United States, Japan, and Europe [3][4][5][6][7][8]. These studies established the sensitivity of low-dose CT for early lung cancer detection. These trials also tested algorithms for diagnostic workup and demonstrated a reduction in the incidence of advanced non-small-cell lung cancer with screening. A high percentage (84-93 %) was Stage I lung cancers [3][4][5]. They also produced somewhat similar results. They demonstrated that detection of earlystage lung cancer was higher than that reported previously with standard chest radiography [9] but that the false positive rate was at least three times that of standard radiographs. In regard to diagnostic algorithms, these studies provided evidence that peripheral nodules greater than 8-10 mm in size required further investigation because of the high likelihood of lung cancer. Such investigations included further imaging with PET-CT, percutaneous biopsy or resection and often led to invasive procedures. Smaller nodules (\8 mm diameter) could be managed with CT follow-up to determine interval growth indicating the likelihood of malignancy.These single arm feasibility and observational studies provided compelling evidence of the effectiveness of helical and MDCT as a screening tool for early detection of lung cancer. However, they were not sufficient to determine screening effectiveness because they were not able to assess the influence of CT screening on lung cancer mortality. Only randomized controlled trials can determine effectiveness of screening where the end point must be a decrease in mortality in the screened group as compared to a non-screened control.Subsequently, several prospective randomized controlled trials were undertaken both in the United States and Europe. These included the National Lung Cancer Screening Trial (NLST) in the United States [10] and the Nelson Trial and others in Europe [11][12][13][14][15]. The results of the NLST trial were published in 2...

Using Speed of Sound Imaging to Characterize Breast Density

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“…Measuring breast density is ultimately a measure of the amount of white regions in the image and can be done both qualitatively and quantitatively. Mammographic percent density (MPD) is defined as the ratio of dense breast tissue relative to the total amount of breast tissue seen on a mammogram and is measured using computer-assisted programs such as Cumulus (Byng, et al 1994) or can be measured volumetrically using programs such as Volpara (Eng, et al 2014, Jeffreys, et al 2010) and Quantra (Ciatto, et al 2012, Regini, et al 2014). However, despite being the current gold standard for breast imaging, mammography poses some shortcomings for the measurement of breast density (Kopans 2008, Sak, et al 2015).…”

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Comparison of digital tomosynthesis and computed tomography for lung nodule detection in SOS screening program

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