title: Subcentimeter lung nodules stable for 2 years at LDCT: long-term follow-up using volumetry.
abstract: OBJECTIVE
  Subcentimeter nodules without change in size during long-term follow-up period (for minimum 2 years) are assumed as benign lesions. However, the 2-year stability rule has not been fully verified so far and is still questionable. Thus, we aimed to retrospectively investigate long-term follow-up results for 2-year stable subcentimeter nodules at screening low-dose computed tomography (LDCT).
  
  
  METHODS
  A total of 635 subjects having had follow-up LDCTs for the initial 2-year screening period and additional 3 years thereafter and having had non-calcified subcentimeter nodules were included. By using computed tomography (CT) nodule volumetry software, we measured interval changes in nodule volume.
  
  
  RESULTS
  A total of 1107 subcentimeter nodules (1037 solid, 70 ground-glass opacity nodules (GGNs)) were detected at baseline CT. Of 1037 solid nodules, 1032 showed no growth during the initial 2-year and 5-year follow-up period. Fifty-nine GGNs were stable for initial 2 years, but two (3.4%) were later proved as adenocarcinomas. Among five solid nodules that showed growth during the initial 2-year follow-up period, one (20%) proved to be an adenocarcinoma, whereas four (36.4%) of 11 GGNs that demonstrated growth were diagnosed as lung cancers.
  
  
  CONCLUSIONS
  All solid subcentimeter nodules having initial 2-year stability at screening LDCT can be considered benign because none shows growth at further follow-up CT. On the other hand, subcentimeter GGNs have more chance of growth than solid nodules and need further follow-up CT for more than 2 years.
authors.affiliation: Department of Radiology and Center for Imaging Science, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Kyung Eun
authors.initials: KE
authors.lastname: Shin
authors.forename: Kyung Soo
authors.initials: KS
authors.lastname: Lee
authors.forename: Chin A
authors.initials: CA
authors.lastname: Yi
authors.forename: Myung Jin
authors.initials: MJ
authors.lastname: Chung
authors.forename: Myung-Hee
authors.initials: MH
authors.lastname: Shin
authors.forename: Yoon-Ho
authors.initials: YH
authors.lastname: Choi
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D018450:Disease Progression; D055088:Early Detection of Cancer / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D003074:Solitary Pulmonary Nodule / Q000175:diagnosis* / Q000000981:diagnostic imaging* / Q000473:pathology; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods*; D047368:Tumor Burden
keywords: ground-glass opacity nodule; low-dose computed tomography; lung cancer screening; solid nodule; subcentimeter nodule