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INTRODUCTION

Learning Objectives

  • The student will be able to describe the epidemiology and risk factors for lung cancer.

  • The student will be able to enumerate the major histologic types of lung cancer and differentiate how cell types affect tumor growth and behavior.

  • The student will be able to recognize the common symptoms and signs of thoracic and extrathoracic lung cancer, and the common paraneoplastic syndromes associated with lung cancer.

  • The student will be able to summarize the general principles of lung cancer staging and describe how tumor stages affect treatment options and outcomes.

EPIDEMIOLOGY AND RISK FACTORS

Lung cancer is the leading cause of cancer-related mortality in the United States. In 2009, over 200,000 new cases of lung cancer were diagnosed and, unfortunately, nearly 160,000 deaths occurred as a result of lung cancer (Fig. 32.1). In a sobering testament to its lethality, lung cancer accounts for only 15% of all cancers diagnosed (excluding non-melanomas of the skin), but accounts for 28% of those cancer deaths. Lung cancer has been the leading cause of cancer death in men in the United States since the mid-1950s, and in women since the late 1980s. This is especially striking given that lung cancer was a rare occurrence at the turn of the 20th century (Fig. 32.2).

FIGURE 32.1

Ten leading cancer types for estimated new cancer cases and deaths in the United States for 2010. From Jemal A et al: Cancer statistics, 2010, CA Cancer J. Clin Sep-Oct;60(5): 277-300, 2010.

FIGURE 32.2

Annual age-adjusted death rates for males (a) and females (b) in the United States for 2010. From Jemal A et al: Cancer statistics, 2010, CA Cancer J. Clin Sep-Oct;60(5): 277-300, 2010.

The incidence of lung cancer increases steadily with age. Over a lifetime, 1 in 13 American men and 1 in 16 American women will be diagnosed with lung cancer. Thankfully, the lung cancer death rate has been declining in men and seems to have reached a plateau in women. African-American men are disproportionally affected compared to other races and ethnicities.

Exposure to tobacco smoke is by far the most substantial risk factor for development of lung cancer, and is at least partially avoidable. Approximately 80%-90% of all patients diagnosed with lung cancer are either current or former smokers. The association between tobacco smoke and lung cancer was postulated a century ago and clearly demonstrated by epidemiologic studies in the 1950s (Fig. 32.3). In the United States, the lifetime risk of lung cancer for a nonsmoker is <1% and increases to 15%-30% with long-term tobacco use. The risk of lung cancer increases with the amount and duration of tobacco exposure, and conversely the risk declines with abstinence. A decrease in risk can be demonstrated within 5 years of quitting smoking, and by 15 years there is an 80%-90% reduction in the risk of developing lung cancer, although that risk remains higher than for a never-smoker. Cigarettes seem to confer a higher risk of lung cancer than the use of pipes and cigars. Passive or "second-hand" exposure to tobacco smoke also increases the risk of lung cancer, but to a much lesser degree than active smoking. Never-smoking women married to husbands who smoke have up to a two-fold increase in the risk of lung cancer compared to never-smoking women with nonsmoking spouses.

FIGURE 32.3

Relationship between cigarette consumption and lung cancer death rates. From Cancer Statistics ...

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