| Abstract: |
1.Patients with Stage 1 lung cancer detected by cytology or x-ray, and treated by complete resection, have a high probability of survival. 2. Sputum cytology is effective in early detection of slow growing squamous (epidermoid) carcinomas of lung, which in our population account for less than one-third of cases. Without cytologic screening these cancers would be identified by annual chest x-rays at a later date, though still while localized and resectable. Thus, in a program of annual chest x-rays, conscientiously carried out, the addition of cytologic screening has no statistically significant effect on mortality. 3. Nearly half of all lung cancers in our population are adenocarcinoma, and early detection of these tumors is virtually restricted to the chest x-ray. Fifteen percent of cases are oat cell (small cell anaplastic) carcinoma, and these rapidly developing tumors are almost all discovered in an advanced stage with symptoms. 4. All participants in our study were offered annual chest x-rays, and no direct evaluation of the effect of radiographic screening on lung cancer mortality was possible. However, 40% of all lung cancers were detected in Stage 1, and at least two-thirds of patients with Stage 1 lung cancer treated by complete resection do not die of that disease. The overall five-year survival of patients enrolled in this program who developed lung cancer is 35%, in contrast to 13% for lung cancer in the United States as a whole. Survival at 10 years for all lung cancer patients in this screening program is 25%, and for those with Stage 1 lung cancer it is approximately 65%. 5. Survival of patients with asymptomatic lung cancer discovered by chest x-rays taken during the couse of a routine physical examination or while under a physician's care for another illness, without regard to stage, is significantly better than for symptomatic lung cancer (35% at 7 years compared with 13%), and approaches the survival of patients with lung cancer detected by screening (45% at 7 years). |
