Among patients with lung cancer detected by computed tomography (CT) screening, those with smaller tumors were significantly less likely to have identifiable metastases than those with larger tumors. These results were published in the Archives of Internal Medicine.
In the U.S. and Europe, lung cancer is the leading cause of cancer deaths. Lung cancer is often detected at a late stage, when it is incurable. This has prompted interest in whether screening healthy individuals for lung cancer could identify the disease at an earlier stage and improve survival.
Among patients with lung cancer detected because of symptoms, smaller tumors are linked with a better prognosis. There is less information, however, about the relationship between tumor size and prognosis in asymptomatic individuals whose lung cancer is detected by screening.
To evaluate the relationship between tumor size and the presence or absence of spread to lymph nodes or distant sites in the body, researchers analyzed information from a large international lung cancer screening trial. The study enrolled 28,689 men and women who had no symptoms of lung cancer. Subjects received baseline and repeat screening for lung cancer using computed tomography (CT). The median patient age was 61 years.
A total of 464 cases of lung cancer were identified by screening. For both non-small cell lung cancer (NSCLC) and small-cell lung cancer (SCLC), patients with smaller tumors were more likely to be free of metastases:
- For patients with NSCLC, the overall proportion of patients who were free of metastases was 85%. The proportion free of metastases ranged form 55% for patients with tumors that were 36 mm or larger, to 91% for patients with tumors that were 15 mm or smaller.
- There were only 28 cases of SCLC. Overall, 46% of these patients were free of metastases. Among SCLC patients with tumors that were 25 mm or smaller, 67% were free of metastases. Among SCLC patients with tumors that were larger than 25 mm, 23% were free of metastases.
The researchers conclude that these results provide direct evidence of a relationship between lung cancer size and stage in patients screened by CT. Smaller tumors were less likely to have spread to lymph nodes or distant sites in the body.
Reference: The International Early Lung Cancer Action Program Investigators. Computed Tomographic Screening for Lung Cancer: The Relationship of Disease Stage to Tumor Size. Archives of Internal Medicine. 2006:166:321-325.
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