title: Wide range and variation in minimally invasive surgery for renal malignancy in Japan: a population-based analysis.
abstract: BACKGROUND
  Despite increasing interest in minimally invasive surgery, prevalence data are completely absent. Our objective was to analyze clinico-epidemiological variations of surgery for renal malignancy in Japan with emphasis on annual trends and regional gaps, and to analyze factors affecting choice of open versus minimally invasive surgery.
  
  
  METHODS
  We identified patients who underwent open (n = 8646), laparoscopic (n = 5932), or minimum incision endoscopic surgery (MIES) (n = 381) nephrectomy for renal malignancy, using the Japanese Diagnosis Procedure Combination database, 2007-2010. Clinical and regional variations in these three approaches were determined, and the annual per-population incidence of nephrectomy was estimated. Multivariate logistic regression was used to analyze factors affecting choice of minimally invasive surgery (laparoscopy or MIES).
  
  
  RESULTS
  The proportion of open nephrectomy decreased from 65.3 % in 2007 to 51.6 % in 2010. Laparoscopic nephrectomy accounted for 51.0 % of procedures for T1 tumors. The estimated incidence of nephrectomy in males and females was 14.3 and 6.1 per 100,000 person-years, respectively. Multivariate analysis showed that minimally invasive nephrectomy was more likely to be selected for patients in their 30-50s who had less comorbidity, better performance status, or lower TNM stage, in high-volume or academic hospitals, especially in western Japan. Hemodialysis use was a favorable factor.
  
  
  CONCLUSIONS
  Despite differences between eastern and western Japan, minimally invasive surgery is becoming widespread throughout Japan, especially for patients with low operative risks and early-stage cancer who are hospitalized in high-volume institutes.
authors.affiliation: Department of Urology, Shintoshi Hospital, Iwata, Japan, ezy04707@nifty.com.
authors.forename: Toru
authors.initials: T
authors.lastname: Sugihara
authors.forename: Hideo
authors.initials: H
authors.lastname: Yasunaga
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Horiguchi
authors.forename: Nobuo
authors.initials: N
authors.lastname: Tsuru
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Fujimura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nishimatsu
authors.forename: Haruki
authors.initials: H
authors.lastname: Kume
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ohe
authors.forename: Shinya
authors.initials: S
authors.lastname: Matsuda
authors.forename: Kiyohide
authors.initials: K
authors.lastname: Fushimi
authors.forename: Yukio
authors.initials: Y
authors.lastname: Homma
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D004724:Endoscopy; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007680:Kidney Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000601:surgery*; D010535:Laparoscopy; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures; D009392:Nephrectomy; D016896:Treatment Outcome