title: CT detection of hydronephrosis in resected colorectal cancer: a predictor of recurrent disease.
abstract: OBJECTIVE
  To investigate the causes and significance of hydronephrosis in follow-up of colorectal cancer.
  
  
  METHODS
  Case notes and serial computed tomography (CT) examinations were reviewed of 75 patients (250 CT examinations) after resection for colorectal cancer in whom hydronephrosis developed on follow-up.
  
  
  RESULTS
  The most common cause of hydronephrosis was a focal plaque-like mass centred on the peritoneum, demonstrated in 37 cases (49%). Patients with R1 (microscopic residual tumour) or R2 (macroscopic residual tumour) disease developed hydronephrosis at a median time of 13 months (90% CI: 9-18 months) compared with 22 months (90% CI: 17-26 months) for those having (R0) curative resection. Patients with pT4 invasion of peritoneum or adjacent organs developed hydronephrosis at a median of 14 months (90% CI: 6-16 months) compared with a median of 22 months in patients with pT3 tumours (90% CI: 11-27 months). Of 26 patients without an obvious cause of hydronephrosis on initial CT examination, follow-up CT demonstrated a definite mass lesion in 50%. Median survival after the onset of hydronephrosis was 6 months (range 1-34 months) with a 1-year mortality of 62%.
  
  
  CONCLUSIONS
  Hydronephrosis is an important early indicator of colorectal cancer recurrence, even in the absence of a mass.
authors.affiliation: Department of Diagnostic Radiology, Royal Marsden Hospital, London, UK. gina.brown@rmh.nthames.nhs.uk
authors.forename: G
authors.initials: G
authors.lastname: Brown
authors.forename: A E
authors.initials: AE
authors.lastname: Drury
authors.forename: D
authors.initials: D
authors.lastname: Cunningham
authors.forename: J E S
authors.initials: JE
authors.lastname: Husband
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006869:Hydronephrosis / Q000000981:diagnostic imaging* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000150:complications / Q000000981:diagnostic imaging*; D018365:Neoplasm, Residual; D010537:Peritoneum / Q000473:pathology; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014517:Ureteral Obstruction / Q000000981:diagnostic imaging / Q000209:etiology