title: Natural history of small, "indeterminate" hepatic lesions in patients with colorectal cancer.
abstract: OBJECTIVE
  The initial staging CT scan for patients with colorectal cancer may reveal small, "indeterminate" hepatic lesions. The significance of these lesions is often unknown at the time of diagnosis. Surveillance of these lesions is often recommended because they may have an impact on the subsequent management of these patients. This study was designed to determine the prevalence and significance of small (<1 cm on CT scan), indeterminate liver lesions detected preoperatively in patients with colorectal cancer and to determine whether further surveillance imaging of these patients is required.
  
  
  METHODS
  Data were collected retrospectively, from January 1, 2002, to December 31, 2005. All colorectal cancer patients with small, indeterminate liver lesions on their initial staging CT scan were included. These lesions were formally reported as being too small to be characterized. All subsequent surveillance images of the liver were reviewed to assess the natural history of these lesions.
  
  
  RESULTS
  Four hundred nineteen patients with colorectal cancer had staging CT performed. Seventy patients (16.7%) had small liver lesions on their initial CT that could not be definitely characterized. Forty-six (65.7%) underwent subsequent imaging of their liver lesions. Forty-one (89.1%) of these were shown to be stable lesions that were likely benign. Only five patients (10.9%) showed progression on subsequent liver imaging, suggestive of early metastases and consistent with their clinical picture.
  
  
  CONCLUSIONS
  Small, indeterminate liver lesions may occur in up to 16.7% of patients with colorectal cancer. Although most of these lesions remain quiescent, surveillance imaging is recommended because a small but not insignificant proportion of patients with such lesions actually harbor early metastases.
authors.affiliation: Division of Colorectal Surgery, Department of Surgery, National University Hospital, Singapore.
authors.forename: Geok-Hoon
authors.initials: GH
authors.lastname: Lim
authors.forename: Dean Chi-Siong
authors.initials: DC
authors.lastname: Koh
authors.forename: Wai-Kit
authors.initials: WK
authors.lastname: Cheong
authors.forename: Kutt-Sing
authors.initials: KS
authors.lastname: Wong
authors.forename: Charles Bih-Shiou
authors.initials: CB
authors.lastname: Tsang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000556:secondary*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D015995:Prevalence; D011379:Prognosis; D012189:Retrospective Studies; D012846:Singapore / Q000453:epidemiology; D014057:Tomography, X-Ray Computed