The early diagnosis of lung cancer

Lung cancer is the most common fatal malignancy in both men and women, both in the United States and elsewhere in the world. Today, lung cancer is mos t often diagnosed on the basis of symptoms of advanced disease or when ches t x-rays are taken for a variety of purposes unrelated to lung cancer detec tion. Unfortunately, in the United States no society or governmental agency recommends screening, even for patients with high risks, such as smokers w ith airflow obstruction or people with occupational exposures, including as bestos. The origins of this negative attitude toward lung cancer screening are found in 3 studies sponsored by the National Cancer Institute in the mi d-1970s and conducted at Johns Hopkins University School of Medicine, the M ayo Clinic, and the Memorial Sloan-Kettering Center. These studies conclude d that early identification of lung cancer through chest x-rays and cytolog ic diagnosis of sputum did not alter disease-specific mortality. However, p atients with earlier stage disease were found through screening, which resu lted in a higher resectability rate and improved survival in the screening group compared with a control group of patients receiving ordinary care. Pa tients in the control group often received annual chest x-rays during the c ourse of this study, which was the standard of care at the time. Thus no tr ue nonscreening control group resulted. The patients at highest risk were not enrolled in this study. No specific a mount of pack-years of smoking intensity was required. Only men were screen ed. The studies were inadequately powered to show an improvement in mortali ty rate of less than 50%. Ninety percent of lung cancer occurs in smokers. The prevalence of lung can cer is to 6 times greater when smokers have airflow obstruction than with n ormal airflow, when all other background factors, including smoking history , occupational risk, and family history, are the same. Screening heavy smok ers {ie, greater than or equal to 30 pack-years) with airflow obstruction { forced expiratory volume in one second < 70% of normal) will yield 2% or mo re patients with lung cancer (prevalence cases) and, over the course of 5 y ears, probably from 2 % to 3 % of patients with additional cancers, yieldin g an overall incidence of 5%. New technologies include low-dose helical com puted tomographic scans for small peripheral adenocarcinomas that cannot ye t be visualized by standard chest x-rays and cytologic diagnosis of sputum for central squamous cell lesions. These tests are complementary. A new health care initiative, the National Lung Health Education Program, r ecommends spirometric testing for all smokers 45 years or older, as well as for patients with symptoms of lung cancer. Screening for lung cancer in su ch patients will find many cancers at an early stage when they are amenable to cure. Today, we have the knowledge and the technology that could change the outcome of lung cancer.