The adenocarcinoma-specific stage shift in the Anti-lung Cancer Association project: significance of repeated screening for lung cancer for more than 5 years with low-dose helical computed tomography in a high-risk cohort.

BACKGROUND

We investigated whether a stage shift occurs during long-term repeated screening for lung cancer with low-dose helical computed tomography (LDCT) in a high-risk cohort.

METHODS

A total of 2120 subjects (mean age, 63 years; 87% male and 83% smokers) were continuously recruited and underwent repeated screening with LDCT from 1993 through 2004.

RESULTS

Nineteen lung cancers were detected at baseline examinations (prevalence cancers), and 57 lung cancers were detected at subsequent examinations (incidence cancers). For both prevalence cancers and incidence cancers, adenocarcinoma (74% and 63%, respectively), especially invasive adenocarcinoma (42% and 23%, respectively), was the most common histological diagnosis, and stage IA was the most common pathological stage (58% and 79%, respectively). The detection rate of incidence cancers other than bronchioloalveolar carcinoma became significantly higher after 5 years of LDCT examinations (r=0.50, P=0.020). Moreover, both the percentage of cancers of stage II-IV and tumor size became significantly lower for invasive adenocarcinoma after 5 years of LDCT examinations (r=-0.77, P=0.007 and r=-0.60, P=0.029, respectively).

CONCLUSIONS

Repeated screening for more than 5 years might demonstrate the efficacy of LDCT screening for lung cancer through an adenocarcinoma-specific stage shift.