title: Growth rate of lung cancer recognized as small solid nodule on initial CT findings.
abstract: BACKGROUND
  To study the characteristics of lung cancer, appearing as small solid nodules on initial computed tomography (CT) findings, and to determine an appropriate follow-up duration so as to differentiate between malignancy and benign tumor.
  
  
  METHODS
  We analyzed the records of 34 patients who had undergone surgical resection of lung cancer, which appeared as small solid nodules on initial CT findings. We studied the CT findings, volume doubling times (VDT), follow-up durations, pathological and clinical findings.
  
  
  RESULTS
  VDT is classified as follows: (1) slow growth group (SGG), with a VDT of more than 700 days and (2) rapid growth group (RGG), with a VDT of less than 700 days. The median VDT of the SGG was 1083 days, and the RGG was 256 days (p<0.01). The median duration for follow-up of the SGG was 1218 days, and 179 days for the RGG. A statistical difference was noted in the follow-up durations (p<0.01). There were no statistical differences in the preoperative thin-section CT (TSCT) findings, or in the pathological findings. The RGG included more patients with smoking histories. The CT findings of RGG tended to reveal changed in base lung field such as emphysema, and lung fibrosis.
  
  
  CONCLUSIONS
  Generally, lung cancer appearing as small solid nodules on initial CT findings grew rapidly, but there were some cases which displayed slow growth patterns. These cases required follow up for over two years, before diagnosis was possible. We concluded the appropriate maximum followup duration is three years.
authors.affiliation: Department of Thoracic Oncology, Kanagawa Cancer Center, 1-1-2 Nakao, Asahi-ku, Yokohama 241-0815, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Mikita
authors.forename: Haruhiro
authors.initials: H
authors.lastname: Saito
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sakuma
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Kondo
authors.forename: Takeshi
authors.initials: T
authors.lastname: Honda
authors.forename: Syuji
authors.initials: S
authors.lastname: Murakami
authors.forename: Fumihiro
authors.initials: F
authors.lastname: Oshita
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ito
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tsuboi
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Nakayama
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yokose
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Kameda
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Noda
authors.forename: Kouzo
authors.initials: K
authors.lastname: Yamada
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000000981:diagnostic imaging / Q000473:pathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000000981:diagnostic imaging* / Q000473:pathology*; D014057:Tomography, X-Ray Computed / Q000379:methods*