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) were divided into three groups: rapid (DT , 183 d), typical (DT 183-365 d), and slow (DT . 365 d). Adenocarcinoma/bronchioloalveolar carcinoma comprised 86.7% 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.Keywords: lung cancer; doubling times; lung cancer screening Computed tomography (CT) screening for lung cancer has been under study for over a decade. With the publication of results from the National Lung Screening Trial (NLST) (1), CT screening for lung cancer may become widespread. We have accumulated over 150 lung cancers as part of the Pittsburgh Lung Screening Study (PLuSS), which started enrolling subjects in 2002 (2). Although there have been several studies of volumetric evaluation of lung nodule doubling times (DTs) for differentiating benign versus malignant pulmonary nodules (3-5), there is less information about DTs in screening-detected lung cancers. We present software volumetric evaluation of DTs in 63 non-small cell lung cancers (NSCLCs) from PLuSS and compare the doubling times in prevalent and nonprevalent cancers.
METHODSPLuSS involved 3,642 subjects and was approved by the Institutional Review Board of the University of Pittsburgh. Written informed consent was obtained from all participants, and the study was compliant with the Health Insurance Portability and Accountability Act. At the time of this study, 148 lung cancers had been diagnosed; 63 were suitable for volumetric nodule analysis.
CT Imaging and Nodule Classification ProtocolCT scans evaluated for volumetric analysis included lung cancer scre...