Does the survivor function estimated after running a Proportional Hazards model give valid predicted probabilities of an event happening after a number of time periods?
The only source I've found on this question says that Proportional Hazards estimates can only be used to discern the factor that two hazards rates differ by when comparing two different levels of an independent variable. They argue that the survivor function is invalid because proportional hazards models (like Cox) do not estimate an underlying hazard function, and so it is impossible to say what the actual predicted hazard is at any point.
According to this powerpoint, the answer is no.
I haven't been able to find any other sources that agree or disagree with their claim that proportional hazards models are only useful for comparisons among hazard rates.