Chapter 085. Neoplasms of the Lung (Part 6)

Diagnosis and StagingScreeningMost patients with lung cancer present with advanced disease, raising the question of whether screening would detect these tumors at an earlier stage when they are theoretically more curable. The role of screening high-risk patients (for example current or former smokers 50 years of age) for early stage lung cancers is debated. Results from five randomized screening studies in the 1980s of chest xrays with or without cytologic analysis of sputum did not show any impact on lung cancer–specific mortality from screening high-risk patients, although earlier-stage cancers were detected in the screened groups. These studies have been...
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Chapter 085. Neoplasms of the Lung (Part 6) Chapter 085. Neoplasms of the Lung (Part 6) Diagnosis and Staging Screening Most patients with lung cancer present with advanced disease, raising thequestion of whether screening would detect these tumors at an earlier stage whenthey are theoretically more curable. The role of screening high-risk patients (forexample current or former smokers >50 years of age) for early stage lung cancersis debated. Results from five randomized screening studies in the 1980s of chest x-rays with or without cytologic analysis of sputum did not show any impact on lungcancer–specific mortality from screening high-risk patients, although earlier-stagecancers were detected in the screened groups. These studies have been criticizedfor their design and statistical analyses, but they led to current recommendationsnot to use these tools to screen for lung cancer. However, low-dose, noncontrast,thin-slice, helical, or spiral CT has emerged as a possible new tool for lung cancerscreening. Spiral CT is a scan in which only the pulmonary parenchyma isexamined, thus negating the use of intravenous contrast and the necessity of aphysician being present at the exam. The scan can usually be done quickly (withinone breath) and involves low doses of radiation. In a nonrandomized study ofcurrent and former smokers from the Early Lung Cancer Action Project (ELCAP),low-dose CT was shown to be more sensitive than chest x-ray for detecting lungnodules and lung cancer in early stages. Survival from date of diagnosis is alsolong (10-year survival predicted to be 92% in screening-detected stage I NSCLCpatients). Other nonrandomized CT screening studies of asymptomatic current orformer smokers also found that early lung cancer cases were diagnosed more oftenwith CT screening than predicted by standard incidence data. However, no declinein the number of advanced lung cancer cases or deaths from lung cancer was notedin the screened group. Thus, spiral CT appears to diagnose more lung cancerwithout improving lung cancer mortality. Concerns include the influence of lead-time bias, length-time bias, and over-diagnosis (cancers so slow-growing that theyare unlikely to cause the death of the patient). Over-diagnosis is a well-establishedproblem in prostate cancer screening, but it is surprising that some lung cancersare not fatal. However, many of the small adenocarcinomas found as groundglass opacities on screening CT appear to have such long doubling times (>400days) that they may never harm the patient. While CT screening will detect lungcancer in 1–4% of the patients screened over a 5-year period, it also detects asubstantial number of false-positive lung lesions (ranging from 25 to 75% indifferent series) that need follow-up and evaluation. The appropriate managementof these small lesions is undefined. Unnecessary treatment of these patients mayinclude thoracotomy and lung resection, thus adding to the cost, mortality, andmorbidity of treatment. A large, randomized trial of CT screening for lung cancer(National Lung Cancer Screening Trial) involving ~55,000 individuals hascompleted accrual and will provide definitive data in the next several years onwhether screening reduces lung cancer mortality. Until these results becomeavailable, routine CT screening for lung cancer cannot be recommended for anyrisk group. For those patients who want to be screened, physicians need to discussthe possible benefits and risks of such screening, including the risk of false-positive scans that could result in multiple follow-up CTs and possible biopsies fora malignancy that may not be life-threatening. Establishing a Diagnosis of Lung Cancer Once signs, symptoms, or screening studies suggest lung cancer, a tissuediagnosis must be established. Tumor tissue can be obtained by a bronchial ortransbronchial biopsy during fiberoptic bronchoscopy; by node biopsy duringmediastinoscopy; from the operative specimen at the time of definitive surgicalresection; by percutaneous biopsy of an enlarged lymph node, soft tissue mass,lytic bone lesion, bone marrow, or pleural lesion; by fine-needle aspiration ofthoracic or extrathoracic tumor masses using CT guidance; or from an adequatecell block obtained from a malignant pleural effusion. In most cases, thepathologist should be able to make a definite diagnosis of epithelial malignancyand distinguish small cell from non-small cell lung cancer. Staging Patients with Lung Cancer Lung cancer staging consists of two parts: first, a determination of thelocation of tumor (anatomic staging) and, second, an assessment of a patientsability to withstand various antitumor treatments (physiologic staging). In a patientwith NSCLC, resectability ...