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. Author manuscript; available in PMC: 2017 Jan 1.
Published in final edited form as: Int J Radiat Oncol Biol Phys. 2015 Sep 18;94(1):133–138. doi: 10.1016/j.ijrobp.2015.09.014

Table 2. Multivariable Analysis of Overall Survival and Recurrence Free Survival.

Covariate Hazard Ratio(95% CI) P-value
Overall Survival
 Proton vs. Photon RT 2.17 (0.66-7.16) 0.201
 Male vs. Female 3.66 (0.80-16.67) 0.093
Recurrence Free Survival
 Proton vs. Photon RT 1.31 (0.50-3.41) 0.584
 Male vs. Female 2.92 (0.96-8.83) 0.058
 RT CSI dose 0.83 (0.66-1.03) 0.096

Of 88, 88 observations are used in the multivariable COX proportional hazards model. Backward variable selection method with an alpha level of removal of .1 was used. The model was stratified by Date of Diagnosis; RT type was forced in the model.

The following variables were removed from the model: Age at Diagnosis, Location of RT boost, Histology, Residual disease after surgery, days from surgery to RT, RT treatment length, Date of Diagnosis, RT CSI dose (for RFS).