Small-cell carcinoma of the lung detected by CT screening: stage distribution and curability

Abstract

Background: Prognosis is incompletely known for small-cell lung carcinoma (SCLC) detected by CT screening of at-risk subjects.

Methods: A multinational study of baseline and annual repeat CT screening for lung cancer of 48,037 at-risk subjects yielded 48 persons (median age 68 years) with SCLC. Stage (tumor, node, metastasis system) distribution and death rates were compared with those of 7960 usual-care SCLC subjects (chi-square or Fisher exact testing, as appropriate), as reported by the International Association for the Study of Lung Cancer. Cure was estimated by Kaplan-Meier analysis.

Results: Forty-four (92%) of the patients were asymptomatic at screening CT detection of their SCLC; four (8%) presented with cancer-related symptoms before the next scheduled repeat screening. SCLC was diagnosed in clinical stages IA and IV in 16 (33%) and 7 (15%), respectively, of 48 patients, compared to 211 (3%) and 4530 (57%), respectively, of the 7960 patients in the usual-care study (P<0.0001). Tumor diameter was ≤3.0 cm for each of the 16 subjects in clinical stage I. The percentage of clinical stage I SCLC-related deaths within 5 years was lower in the screening study than in the usual-care study (44% vs. 71%, P=0.03), as was also the percentage of advanced stage (IIIB plus IV) SCLC-related deaths (62% vs. 94%, P<0.0001).

Conclusions: Compared to usual-care detection of SCLC, CT screening identified a shift toward early stage and away from late stage disease, and was associated with a decrease in deaths from the disease.