title: Tumor size is associated with compensatory hypertrophy in the contralateral kidney after radical nephrectomy in patients with renal cell carcinoma.
abstract: OBJECTIVE
  To assess the association between tumor size and postoperative compensatory hypertrophy of the contralateral kidney estimated with preoperative and postoperative CT in patients with renal cell carcinoma (RCC).
  
  
  METHODS
  We prospectively identified 728 patients who underwent radical nephrectomy for RCC between 2012 and 2014. Contrast-enhanced CT was done within 3 months preoperatively and 1 year postoperatively. A tissue segmentation tool program with CT images was used to estimate kidney volume. We divided patients into three groups according to tumor size (A: ≤4 cm, B: 4-7 cm, C: >7 cm). Preoperative and postoperative volumetric kidney parameters were compared and multivariable linear regression model was used to analyze predictors associated with postoperative compensatory hypertrophy.
  
  
  RESULTS
  The preoperative median contralateral kidney volume was significantly larger in group C than in groups A and B (A: 170.3, B: 176.9, C: 186.8 mL, p < 0.05); the median tumor-side renal parenchymal volume was smaller in group C than in the other groups (A: 168.4, B: 171.1, C: 139.0 mL, p < 0.001). However, the postoperative median contralateral kidney volume among the three groups was not significantly different; the median contralateral kidney volume change after surgery was significantly larger in groups A and B than in group C (A: 37.8, B: 37.5, C: 27.4 mL, p < 0.05). Tumor size (≤7 cm) (p = 0.001) and male gender (p < 0.001) were significantly correlated with increased contralateral kidney volume on multivariable analysis. Tumor size showed the strongest positive association with postoperative contralateral kidney volume (A vs. C, partial regression coefficient = 10.6; B vs. C, partial regression coefficient = 10.5).
  
  
  CONCLUSIONS
  Tumor size (≤4 or 4-7 cm) and male gender are significant factors associated with compensatory hypertrophy after surgery.
authors.affiliation: Department of Urology, Uijeongbu St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Bong Hee
authors.initials: BH
authors.lastname: Park
authors.affiliation: Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 135-710, Republic of Korea.
authors.forename: Hyun Hwan
authors.initials: HH
authors.lastname: Sung
authors.affiliation: Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 135-710, Republic of Korea.
authors.forename: Byong Chang
authors.initials: BC
authors.lastname: Jeong
authors.affiliation: Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 135-710, Republic of Korea.
authors.forename: Seong Ii
authors.initials: SI
authors.lastname: Seo
authors.affiliation: Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 135-710, Republic of Korea.
authors.forename: Seong Soo
authors.initials: SS
authors.lastname: Jeon
authors.affiliation: Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 135-710, Republic of Korea.
authors.forename: Hyun Moo
authors.initials: HM
authors.lastname: Lee
authors.affiliation: Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 135-710, Republic of Korea.
authors.forename: Han Yong
authors.initials: HY
authors.lastname: Choi
authors.affiliation: Department of Urology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 135-710, Republic of Korea. hwanggyun.jeon@samsung.com.
authors.forename: Hwang Gyun
authors.initials: HG
authors.lastname: Jeon
mesh_terms: D002292:Carcinoma, Renal Cell / Q000473:pathology* / Q000601:surgery; D015331:Cohort Studies; D005260:Female; D006801:Humans; D006984:Hypertrophy / Q000000981:diagnostic imaging / Q000209:etiology; D007668:Kidney / Q000000981:diagnostic imaging / Q000473:pathology*; D007680:Kidney Neoplasms / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009392:Nephrectomy / Q000009:adverse effects*; D009929:Organ Size; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
keywords: Computerized tomography; Hypertrophy; Nephrectomy; Renal cell carcinoma