Q: Screening for early-stage lung cancer is not recommended by the National Cancer Institute (NCI) or the American Cancer Society (ACS). Why, then, should I consider it for my patients who are current or former smokers?
A: Approximately 90% of cases of lung cancer are attributable to smoking— either directly or as a result of passive exposure. Fifty percent of smokers die of a smoking-related disease. The 4 most common causes of death—heart attack, lung cancer, chronic obstructive pulmonary disease, and stroke—are all associated with smoking. More lung cancer is diagnosed in former than in current smokers.1 The risk of lung cancer decreases each year following smoking cessation, but former heavy smokers will always have a higher risk than nonsmokers.
Other lung cancer risks include exposure to industrial chemicals (particularly asbestos), solvents, certain heavy metals and, possibly, radon. But if it were not for tobacco use, lung cancer would be a rare disease instead of what it is today—the most common fatal malignancy in both men and women.
This year, approximately 175,000 new lung cancers will be diagnosed, mostly in advanced and symptomatic stages. Only about 13% of patients will be alive 5 years after diagnosis.2 The reason for this dismal statistic is the lack of any systematic early detection program, even for persons known to be at high risk. Deaths from lung cancer among men are now falling slightly, but the numbers are increasing rapidly in women. The net result is a continuing rise in lung cancer incidence.
The case for screening. Neither the NCI nor the ACS recommends screening for early-stage lung cancer3—a position that I oppose. I have made a strong case for lung cancer screening in high-risk groups.4 Solid evidence exists that in the population of persons with a history of heavy smoking and airflow obstruction as determined by simple spirometry, the prevalence of lung cancer is 3% to 5% during the 5 years after initial screening. This is a very large number compared with the much lower yield of screening programs for breast, prostate, and colon cancers. Early-stage lung cancer has a prognosis comparable to that of other early-stage cancers.5 Thus, early detection is the only way to improve survival.
Today we have the knowledge and technology to detect lung cancer in the early, asymptomatic stages when improved survival and the likelihood of cure are high. Low-dose CT scanning for peripheral lesions and sputum cytology for central lesions can identify most of these cancers. It is time to implement screening programs for high-risk patients. We do not need controlled clinical trials to verify that we can find, treat, and cure lung cancer right now.
