CT screening for lung cancer: suspiciousness of nodules according to size on baseline scans.
OBJECTIVE
To assess the frequency with which a particular, possibly optimal work-up of noncalcified nodules less than 5.0 mm in diameter identified on initial computed tomographic (CT) images at baseline screening leads to a diagnosis of malignancy prior to first annual repeat screening, compared with a possibly optimal work-up of larger nodules.


METHODS
Two series of baseline CT screenings in high-risk people were retrospectively reviewed. The first series (n = 1,000) was performed in 1993-1998; the second (n = 1,897), in 1999-2002. In each series, cases in which the largest noncalcified nodule detected was less than 5.0 mm in diameter and those in which it was 5.0-9 mm were reviewed to determine whether diagnostic work-up prior to first annual repeat screening showed or would have shown nodule growth and led or would have led to a diagnosis based on biopsy or surgical specimens.


RESULTS
The frequency with which malignancy was or could have been diagnosed when the largest noncalcified nodule was less than 5.0 mm in diameter was 0 of 378, whereas when the largest noncalcified nodule was 5.0-9 mm in diameter, the frequency was 13 or 14 of 238. If persons with only nodules smaller than 5.0 mm had merely been referred for first annual repeat screening without immediate further work-up, the referrals for such work-up would have been reduced by 54% (from 817 [28%] to 385 [13%] of 2,897).


CONCLUSIONS
In modern CT screening for lung cancer at baseline, detected noncalcified nodules smaller than 5.0 mm in diameter do not justify immediate work-up but only annual repeat screening to determine whether interim growth has occurred.
Department of Radiology and Medicine, Weill Medical College of Cornell University, 525 E 68th St, New York, NY 10021, USA. chensch@med.cornell.edu
Claudia I
CI
Henschke
David F
DF
Yankelevitz
David P
DP
Naidich
Dorothy I
DI
McCauley
Georgeann
G
McGuinness
Daniel M
DM
Libby
James P
JP
Smith
Mark W
MW
Pasmantier
Olli S
OS
Miettinen
D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000145:classification / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D009367:Neoplasm Staging; D009518:New York; D012189:Retrospective Studies; D003074:Solitary Pulmonary Nodule / Q000145:classification / Q000000981:diagnostic imaging / Q000473:pathology; D014057:Tomography, X-Ray Computed