Corrected Cox Proportional Hazards (Gender as binary)
n = 656, events = 394
Call:
coxph(formula = cox_formula, data = cg_complete)

  n= 656, number of events= 394 

                      coef exp(coef) se(coef)       z Pr(>|z|)    
Grade_groupLGG    -1.25121   0.28616  0.11004 -11.371   <2e-16 ***
Gender_binaryMale  0.03271   1.03325  0.10240   0.319   0.7494    
Age_scaled         0.12524   1.13343  0.05171   2.422   0.0154 *  
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

                  exp(coef) exp(-coef) lower .95 upper .95
Grade_groupLGG       0.2862     3.4946    0.2306     0.355
Gender_binaryMale    1.0333     0.9678    0.8454     1.263
Age_scaled           1.1334     0.8823    1.0242     1.254

Concordance= 0.674  (se = 0.014 )
Likelihood ratio test= 159.6  on 3 df,   p=<2e-16
Wald test            = 168.7  on 3 df,   p=<2e-16
Score (logrank) test = 190.5  on 3 df,   p=<2e-16


C-index = 0.674
C-index (grade only) = 0.661
