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.
Conclusion: 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.