Lung Cancer.pdf

Thoracic Imaging Techniques 37
Introduction
Lung cancer, an uncommon disease before 1900, became a major health
problem in the 20th century. In the United States, lung cancer is the most
common malignancy and the leading cause of cancer-related deaths in
both men and women. This chapter will review the current applications of
thoracic imaging techniques in lung cancer patients at M.D. Anderson
Cancer Center, including screening for lung cancer, evaluation of focal
pulmonary abnormalities, staging of lung cancer, assessment of response
to treatment, and monitoring for tumor recurrence after treatment.
Screening
Screening for lung cancer—efforts to detect lung cancer before symptoms
develop—has been advocated as a means for improving the prognosis of
patients with this disease. The concept is supported by 2 main observations:
most patients with lung cancer have advanced disease at the time of
clinical presentation, and the diagnosis of lung cancer at an early stage is
usually associated with improved prognosis. However, the role of imaging
in screening is not clearly defined.
Currently, the American Cancer Society does not recommend screening
but rather advocates primary prevention. This recommendation is based
on the results of 4 large randomized trials undertaken in the 1970s that
evaluated the utility of chest radiography and sputum cytology in lung
cancer screening (Kubik et al, 1990; Strauss, 1997). These trials showed
that screening improved long-term survival rates but did not reduce
disease-specific mortality, which is considered the best indicator of screening
effectiveness because mortality is not affected by lead-time bias,
length-time bias, or overdiagnosis bias.
Recently, there has been renewed interest in evaluating lung cancer
screening, in part because of a belief that the older trials were flawed in
design and methodology and also because of advances in radiologic imaging
that have occurred in the interim (Kaneko et al, 1996; Strauss, 1997;
Henschke et al, 1999). In particular, the advent of computed tomography
(CT) has allowed detection of small lung cancers not apparent on conventional
chest radiographs. Two recent small studies have confirmed that
there is increased detection of small lung cancers when CT is used to
screen patients considered to be at high risk for developing lung cancer
(Kaneko et al, 1996; Henschke et al, 1999). In one of these studies, the Early
Lung Cancer Action Project, low-dose helical CT was used to screen for
lung cancer in 1,000 patients (Henschke et al, 1999). Lung cancer was detected
in 2.7% of these patients with CT but in only 0.7% with chest radiography.
Furthermore, 23 (85%) of the 27 lung cancers detected with CT
were stage I, compared to only 4 (67%) of the 7 lung cancers detected with