title: Growth kinetics and short-term outcomes of cT1b and cT2 renal masses under active surveillance.
abstract: OBJECTIVE
  Compared to T1a lesions the natural history of untreated renal masses larger than 4 cm is poorly understood. We assessed the growth kinetics and outcomes of cT1b/T2 cortical renal tumors managed by an initial period of active surveillance. We compared these cases to those treated with definitive delayed intervention.
  
  
  METHODS
  We reviewed our institutional, prospectively maintained renal tumor database to identify enhancing solid and cystic masses managed expectantly. Included in analysis were clinically localized tumors greater than 4.0 cm (T1b or greater) that were radiographically followed for more than 6 months. Tumor size at presentation, annual linear tumor growth rate, Charlson comorbidity index, followup and clinical outcomes were compared in patients who remained on active surveillance and those who underwent delayed surgical intervention.
  
  
  RESULTS
  We identified 72 tumors 4 cm or greater in diameter in a total of 68 patients. Active surveillance was the only treatment in 45 patients (66%) while 23 (34%) progressed to intervention. Median tumor size at presentation was 4.9 cm and the mean linear growth rate was 0.44 cm per year. Of the masses 14.7% demonstrated no growth with time. Comparing patients treated exclusively with active surveillance and those who progressed to definitive intervention revealed no difference in median tumor size at presentation (4.9 vs 4.6 cm, p = 0.79) or the median Charlson comorbidity index (3 vs 2, p = 0.6) but significant differences were seen in median age at presentation (77 vs 60 years, p = 0.0002) and the mean linear growth rate (0.37 vs 0.73 cm per year, p = 0.02). After adjustment younger patients (OR 0.91, 95% CI 0.86-0.97) and tumors with a faster linear growth rate (OR 9.1, 95% CI 1.7-47.8) were more likely to be treated with delayed surgical intervention. At a mean ± SD 38.9 ± 24.0 months of followup (median 32, range 6 to 105) 9 patients (13%) had died of another cause and none had progressed to metastatic disease.
  
  
  CONCLUSIONS
  Localized cT1b or larger renal masses show growth rates comparable to those of small tumors managed expectantly with a low rate of progression to metastatic disease at short-term followup. An initial period of active surveillance to determine tumor growth kinetics is a reasonable option in select patients with significant competing risks and limited life expectancy.
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center-Temple University Health System, Philadelphia, Pennsylvania. Electronic address: reza.mehrazin@fccc.edu.
authors.forename: Reza
authors.initials: R
authors.lastname: Mehrazin
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center-Temple University Health System, Philadelphia, Pennsylvania.
authors.forename: Marc C
authors.initials: MC
authors.lastname: Smaldone
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center-Temple University Health System, Philadelphia, Pennsylvania.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kutikov
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center-Temple University Health System, Philadelphia, Pennsylvania.
authors.forename: Tianyu
authors.initials: T
authors.lastname: Li
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center-Temple University Health System, Philadelphia, Pennsylvania.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Tomaszewski
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center-Temple University Health System, Philadelphia, Pennsylvania.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Canter
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center-Temple University Health System, Philadelphia, Pennsylvania.
authors.forename: Rosalia
authors.initials: R
authors.lastname: Viterbo
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center-Temple University Health System, Philadelphia, Pennsylvania.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Greenberg
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center-Temple University Health System, Philadelphia, Pennsylvania.
authors.forename: David Y T
authors.initials: DY
authors.lastname: Chen
authors.affiliation: Division of Urologic Oncology, Department of Surgical Oncology, Fox Chase Cancer Center-Temple University Health System, Philadelphia, Pennsylvania.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Uzzo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology*; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D013997:Time Factors; D047368:Tumor Burden; D057832:Watchful Waiting
keywords: carcinoma; disease progression; kidney neoplasms; prognosis; renal cell; watchful waiting