Doubling times and CT screen-detected lung cancers in the Pittsburgh lung screening study

Rationale: As computed tomography (CT) screening for lung cancer becomes more widespread, volumetric analyses, including doubling times, of CT-screen detected lung nodules and lung cancers may provide useful information in the follow-up and management of CT-detected lung nodules and cancers. Objectives: To analyze doubling times in CT screen detected lung cancers and compare prevalent and nonprevalent cancers and different cell types on non small cell lung cancer. Methods:We performed volumetric and doubling time analysis on 63 non-small cell lung cancers detected as part of the Pittsburgh Lung Screening Study using a commercially available VITREA 2 workstation and VITREA VITAL nodule segmentation software. Measurements and Main Results: Doubling times (DT)weredividedinto three groups: rapid (DT < 183 d), typical (DT 183-365 d), and slow (DT > 365 d). Adenocarcinoma/bronchioloalveolar carcinoma comprised86.7% of the slow DT group compared with 20%of the rapid DT group. Conversely, squamous cell cancer comprised 60% of the rapid DT group compared with 3.3% of the slow DT group. Twenty-eight of 42 (67%) prevalent and 2 of 21 (10%) nonprevalent cancers were in the slow DT group (P < 0.0001; Fisher's exact test). Twenty-four of 32 (75%) prevalent and 1 of 11 (9%) nonprevalent adenocarcinomas were in the slow DT group (P < 0.0002; Fisher's exact test). Conclusions: Volumetric analysis of CT-detected lung cancers is particularly useful in AC/BAC. Prevalent cancers have a significantly slower DT than nonprevalent cancers and a higher percentage of adenocarcinoma/ bronchioloalveolar carcinoma. These results should affect the management of indeterminant lung nodules detected on screening CT scans.