[R] survival probability estimate method

[array chip]

Hi, I was reading a paper published in JCO "Prediction of risk of distant recurrence using 21-gene recurrence score in node-negative and node-positive postmenopausal patients with breast cancer treated with anastrozole or tamoxifen: a TransATAC study" (ICO 2010 28: 1829). The author uses a method to estimate the 9-year risk of distant recurrence as a function of continuous recurrence score (RS). The method is special as author states:
 
"To define the continuous relation between RS, as a linear covariate, and 9-year risk of distant recurrence, the logarithm of the baseline cumulative hazard function was fitted by constrained cubic splines with 3 df. These models tend to be more robust for prediction of survival probabilities and corresponding confidence limits at late follow-up time as a result of the modeling of the baseline cumulative hazard function by natural cubic splines (in contrast to using the crude hazard function itself)."
 
Does R provide a package/function to do this particular method for estimating survival probability as a function of a continuous variable? Is the survest.cph() in rms package doing estimation with just the crude hazard function?
 
Thanks very much!
 
John