title: Active surveillance of small renal masses: progression patterns of early stage kidney cancer.
abstract: BACKGROUND
  Most early stage kidney cancers are renal cell carcinomas (RCCs), and most are diagnosed incidentally by imaging as small renal masses (SRMs). Indirect evidence suggests that most small RCCs grow slowly and rarely metastasize.
  
  
  OBJECTIVE
  To determine the progression and growth rates for newly diagnosed SRMs stratified by needle core biopsy pathology.
  
  
  METHODS
  A multicenter prospective phase 2 clinical trial of active surveillance of 209 SRMs in 178 elderly and/or infirm patients was conducted from 2004 until 2009 with treatment delayed until progression.
  
  
  METHODS
  Patients underwent serial imaging and needle core biopsies.
  
  
  METHODS
  We measured rates of change in tumor diameter (growth measured by imaging) and progression to ≥ 4 cm, doubling of tumor volume, or metastasis with histology on biopsy.
  
  
  CONCLUSIONS
  Local progression occurred in 25 patients (12%), plus 2 progressed with metastases (1.1%). Of the 178 subjects with 209 SRMs, 127 with 151 SRMs had>12 mo of follow-up with two or more images, with a mean follow-up of 28 mo. Their tumor diameters increased by an average of 0.13 cm/yr. Needle core biopsy in 101 SRMs demonstrated that the presence of RCC did not significantly change growth rate. Limitations included no central review of imaging and pathology and a short follow-up.
  
  
  CONCLUSIONS
  This is the first SRM active surveillance study to correlate growth with histology prospectively. In the first 2 yr, the rate of local progression to higher stage is low, and metastases are rare. SRMs appear to grow very slowly, even if biopsy proven to be RCC. Many patients with SRMs can therefore be initially managed conservatively with serial imaging, avoiding the morbidity of surgical or ablative treatment.
authors.affiliation: Division of Urology, Department of Surgery and of Surgical Oncology, Princess Margaret Hospital and the University Health Network, University of Toronto, Toronto, Ontario, Canada. m.jewett@utoronto.ca
authors.forename: Michael A S
authors.initials: MA
authors.lastname: Jewett
authors.forename: Kamal
authors.initials: K
authors.lastname: Mattar
authors.forename: Joan
authors.initials: J
authors.lastname: Basiuk
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Morash
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Pautler
authors.forename: D Robert
authors.initials: DR
authors.lastname: Siemens
authors.forename: Simon
authors.initials: S
authors.lastname: Tanguay
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Rendon
authors.forename: Martin E
authors.initials: ME
authors.lastname: Gleave
authors.forename: Darrel E
authors.initials: DE
authors.lastname: Drachenberg
authors.forename: Raymond
authors.initials: R
authors.lastname: Chow
authors.forename: Hannah
authors.initials: H
authors.lastname: Chung
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Chin
authors.forename: Neil E
authors.initials: NE
authors.lastname: Fleshner
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Evans
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Gallie
authors.forename: Masoom A
authors.initials: MA
authors.lastname: Haider
authors.forename: John R
authors.initials: JR
authors.lastname: Kachura
authors.forename: Ghada
authors.initials: G
authors.lastname: Kurban
authors.forename: Kimberly
authors.initials: K
authors.lastname: Fernandes
authors.forename: Antonio
authors.initials: A
authors.lastname: Finelli
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D002292:Carcinoma, Renal Cell / Q000473:pathology* / Q000628:therapy*; D018450:Disease Progression; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology* / Q000628:therapy*; D008875:Middle Aged; D009367:Neoplasm Staging; D011159:Population Surveillance; D011446:Prospective Studies