title: Impact of age on the cancer-specific survival of patients with localized renal cell carcinoma: martingale residual and competing risks analysis.
abstract: BACKGROUND
  Age at diagnosis has been shown to be an independent prognostic factor of localized renal cell carcinoma (RCC) in several studies. We used contemporary statistical methods to reevaluate the effect of age on the cancer-specific survival (CSS) of localized RCC.
  
  
  RESULTS
  1,147 patients with localized RCC who underwent radical nephrectomy between 1993 and 2009 were identified in our four institutions. The association between age and CSS was estimated, and the potential threshold was identified by a univariate Cox model and by martingale residual analysis. Competing risks regression was used to identify the independent impact of age on CSS. The median age was 52 years (range, 19-84 years). The median follow-up was 61 months (range, 6-144 months) for survivors. A steep increasing smoothed martingale residual plot indicated an adverse prognostic effect of age on CSS. The age cut-off of 45 years was most predictive of CSS on univariate Cox analysis and martingale residual analysis (p = 0.005). Age ≤45 years was independently associated with a higher CSS rate in the multivariate Cox regression model (HR = 1.59, 95% CI = 1.05-2.40, p = 0.027) as well as in competing risks regression (HR = 3.60, 95% CI = 1.93-6.71, p = 0.001).
  
  
  CONCLUSIONS
  Increasing age was associated with a higher incidence of cancer-specific mortality of localized RCC. Age dichotomized at 45 years would maximize the predictive value of age on CSS, and independently predict the CSS of patients with localized RCC.
authors.affiliation: Department of Urology, First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Muyan
authors.initials: M
authors.lastname: Cai
authors.forename: Jinhuan
authors.initials: J
authors.lastname: Wei
authors.forename: Zhiling
authors.initials: Z
authors.lastname: Zhang
authors.forename: Hongwei
authors.initials: H
authors.lastname: Zhao
authors.forename: Yunqiao
authors.initials: Y
authors.lastname: Qiu
authors.forename: Yong
authors.initials: Y
authors.lastname: Fang
authors.forename: Zhenli
authors.initials: Z
authors.lastname: Gao
authors.forename: Jiazheng
authors.initials: J
authors.lastname: Cao
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Fangjian
authors.initials: F
authors.lastname: Zhou
authors.forename: Dan
authors.initials: D
authors.lastname: Xie
authors.forename: Junhang
authors.initials: J
authors.lastname: Luo
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000401:mortality* / Q000473:pathology*; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000401:mortality* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D016019:Survival Analysis; D055815:Young Adult