title: Small renal cell carcinomas--how dangerous are they really? Results of a large multicenter study.
abstract: OBJECTIVE
  Modern diagnostic ultrasound and cross-sectional imaging has enabled the detection of increasing numbers of renal tumours. The aim of this study was to investigate the tumour- and patient-specific characteristics and prognosis of small renal cell carcinomas (RCCs) after surgical resection.
  
  
  METHODS
  The study included 2197 patients who underwent surgical resection of histologically confirmed RCC ⩽ 4 cm between 1990 and 2011. Median (mean) follow-up was 56.2 (65.5) months.
  
  
  RESULTS
  At the time of surgery, tumours were staged as pT ⩾ 3a in 175 (8.0%) cases, 134 (6.2%) were poorly differentiated and 75 (3.5%) were metastasised. The larger the tumour size, the higher was the risk of presenting with stage pT ⩾ 3a (p<0.001), poor tumour differentiation (p = 0.004), microscopic vascular involvement (p = 0.001) and collecting system invasion (p = 0.03). The 5-year cancer-specific survival (CSS) rate was 93.8% for stage pT1a versus 79.4% for stage pT ⩾ 3a (p<0.001), and it was 93.7% for G1-2 versus 76.8% for G3-4 differentiation (p<0.001). Multivariate analysis identified age in years (hazard ratio (HR) 1.04, p<0.001), metastatic disease (HR 12.5, p < 0.001), tumour differentiation (HR 2.8, p<0.001) and non-clear cell histology (HR 0.51, p = 0.02) as independent prognosticators for CSS in patients with small RCC. Interestingly, the 5-year cancer-specific mortality rate for pT1a N/M0 patients was 5.8%.
  
  
  CONCLUSIONS
  This large multicenter study has clearly shown that, though most small RCC have a low pathological stage and a good prognosis, there is also a small but significant subgroup of these tumours that are already locally advanced or poorly differentiated.
authors: Department of Urology, Hannover University Medical School, Hannover, Germany. Electronic address: steffens.sandra@mh-hannover.de.
authors: Sandra
authors: S
authors: Steffens
authors: Department of Urology, Saarland University Medical Center, Homburg/Saar, Germany; Department of Urology, Jena University Hospital, Jena, Germany.
authors: Kerstin
authors: K
authors: Junker
authors: Department of Urology, Mainz University Medical Center, Mainz, Germany.
authors: Frederik C
authors: FC
authors: Roos
authors: Department of Urology, Saarland University Medical Center, Homburg/Saar, Germany.
authors: Martin
authors: M
authors: Janssen
authors: Department of Urology, Saarland University Medical Center, Homburg/Saar, Germany.
authors: Frank
authors: F
authors: Becker
authors: Department of Urology, Ulm University Medical Center, Ulm, Germany.
authors: Daniela
authors: D
authors: Henn
authors: Cancer Center, Hannover University Medical School, Hannover, Germany.
authors: Gerd
authors: G
authors: Wegener
authors: Department of Urology, Saarland University Medical Center, Homburg/Saar, Germany.
authors: Stefan
authors: S
authors: Siemer
authors: Department of Urology, Philipps University of Marburg, Marburg, Germany.
authors: Rainer
authors: R
authors: Hofmann
authors: Department of Urology, Ulm University Medical Center, Ulm, Germany.
authors: Mark
authors: M
authors: Schrader
authors: Department of Urology, Saarland University Medical Center, Homburg/Saar, Germany.
authors: Michael
authors: M
authors: Stöckle
authors: Department of Urology, Mainz University Medical Center, Mainz, Germany.
authors: Joachim W
authors: JW
authors: Thüroff
authors: Institute of Pathology, Erlangen University Medical Center, Erlangen, Germany.
authors: Arndt
authors: A
authors: Hartmann
authors: Department of Urology, Hannover University Medical School, Hannover, Germany.
authors: Markus A
authors: MA
authors: Kuczyk
authors: Department of Urology, Ulm University Medical Center, Ulm, Germany; Department of Urology, Philipps University of Marburg, Marburg, Germany.
authors: Andres J
authors: AJ
authors: Schrader
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000401:mortality* / Q000473:pathology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007680:Kidney Neoplasms / Q000401:mortality* / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009392:Nephrectomy; D016019:Survival Analysis; D047368:Tumor Burden / Q000502:physiology*; D055815:Young Adult
keywords: Follow-up; Kidney cancer; Metastasis; Prognosis; Risk factor; Small renal tumours; Survival