Lung Cancers Diagnosed at Annual CT Screening: Volume Doubling Times

Abstract

As the Writing Committee for the I-ELCAP InvestigatorsPurpose:To empirically address the distribution of the volume doubling time (VDT) of lung cancers diagnosed in repeat annual rounds of computed tomographic (CT) screening in the International Early Lung Cancer Action Program (I-ELCAP), first and foremost with respect to rates of tumor growth but also in terms of cell types. Materials and Methods:All CT screenings in I-ELCAP from 1993 to 2009 were performed according to HIPAA-compliant protocols approved by the institutional review boards of the collaborating institutions. All instances of first diagnosis of primary lung cancer after a negative screening result 7-18 months earlier were identified, with symptom-prompted diagnoses included. Lesion diameter was calculated by using the measured length and width of each cancer at the time when the nodule was first identified for further work-up and at the time of the most recent prior screening, 7-18 months earlier. The length and width were measured a second time for each cancer, and the geometric mean of the two calculated diameters was used to calculate the VDT. The x 2 statistic was used to compare the VDT distributions. Results:The median VDT for 111 cancers was 98 days (interquartile range, 108). For 56 (50%) cancers it was less than 100 days, and for three (3%) cancers it was more than 400 days. Adenocarcinoma was the most frequent cell type (50%), followed by squamous cell carcinoma (19%), small cell carcinoma (19%), and others (12%). Lung cancers manifesting as subsolid nodules had significantly longer VDTs than those manifesting as solid nodules (P , .0001). Conclusion:Lung cancers diagnosed in annual repeat rounds of CT screening, as manifest by the VDT and cell-type distributions, are similar to those diagnosed in the absence of screening.q RSNA, 2012

Quantification of growth patterns of screen-detected lung cancers: The NELSON study

“…The median overall VDT of lung cancers in this study was 348 days (IQR: 222-492 days), and comparable to VDTs reported in other lung cancer screening trials [21][22][23]. Since at least three monitoring points are necessary for growth pattern evaluation, lung cancers referred after the first short-term follow-up CT were not included in this analysis.…”

Solitary Pulmonary Nodule—The Role of Imaging in the Diagnostic Process

“…The assessment of a solitary pulmonary nodule following administration of a contrast agent may provide additional information on the nature of the lesion since contrast enhancement is directly related to the lesions' vasculature and good vasculature is usually characteristic of malignant lesions [37,38]. Full evaluation of the degree of enhancement requires a series of scans at intervals of several minutes.…”

“…Nodular enhancement of less than 15 H.U. is suggestive of a benign lesion (false negatives include nodes with central necrosis and adenocarcinoma [37], while the enhancement of 20-60 H.U. is indicative of a malignant lesion [39].…”

The importance of the regimen of screening in maximizing the benefit and minimizing the harms

“…The diameter is calculated as the average of the measured length and width and this is again done on the follow-up images. These two diameter measurements at two time points is used to calculate the volume doubling time (VDT) of the nodule (14,(34)(35)(36)(37)(38). VDTs of less than 30 days are more suggestive of an infection than malignancy.…”

“…Starting with the initial protocol developed for CT screening for lung cancer in 1992 (2-4), the protocol has been continuously updated based on the results of conferences held every 6 months (5,6) and on subsequent data emerging from CT screening (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The protocol has been recently updated, integrating the latest technologies advances and knowledge (21).…”