title: Distant metastasis of renal cell carcinoma with a diameter of 3 cm or less-which is aggressive cancer?
abstract: OBJECTIVE
  It was previously thought that renal cell carcinoma with a diameter of 3 cm or less has low potential to cause distant metastasis. However, metastasis develops in a small number of cases, which cannot be ignored. We investigated the clinicopathological characters of small renal cell carcinoma with metastasis to further understand this condition.
  
  
  METHODS
  From January 1983 to February 2009, 165 cases of sporadic renal cell carcinoma 3 cm or less were treated at our department. Bilateral and von Hippel-Lindau disease were excluded from study. Clinicopathological parameters and outcome data were collected on each patient and analyzed.
  
  
  RESULTS
  Histologically the 165 cases of primary renal cell carcinoma 3 cm or less included 151 of clear cell, 10 of papillary and 4 of chromophobe renal cell carcinoma, of which 4 had sarcomatoid differentiation, 6 had perinephric and/or sinus invasion and 20 had microvascular invasion. Overall we identified 10 metastatic cases (6.06%), of which 5 were synchronous. Univariate analysis revealed that age 60 years or greater (p = 0.0139), symptoms (p = 0.0054) and microvascular invasion (p <0.0001) were significant risk factors. Multivariate analysis showed that only microvascular invasion was a significant risk factor (p = 0.00062). Perinephric and/or sinus fat invasion was not a significant risk factor.
  
  
  CONCLUSIONS
  Metastasis also develops in small renal cell carcinoma cases. Results suggest that microvascular invasion is a significant risk factor and patients with microvascular invasion should be followed more carefully.
authors.affiliation: Department of Urology, Tokyo University Hospital, Tokyo, Japan. kume@kuc.biglobe.ne.jp
authors.forename: Haruki
authors.initials: H
authors.lastname: Kume
authors.forename: Motofumi
authors.initials: M
authors.lastname: Suzuki
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Fujimura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Fukuhara
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Enomoto
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nishimatsu
authors.forename: Yukio
authors.initials: Y
authors.lastname: Homma
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D002292:Carcinoma, Renal Cell / Q000473:pathology* / Q000628:therapy; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis / Q000473:pathology*; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors