Power calculation gene expression survival analysis

Question

[Bine]

Dear all,

I have identified one gene, whose expression influences survival in patients. I tried to replicate the result in another dataset. However, I could not find an effect in another dataset. Most likely due to small sample size.

I would like to do a power calculation.

However, I do not find any example for this specific scenario. Could anyone point me to a e.g. R package or any other suggestion how I could do this?

Thank you!