I have a set of biomarkers (genes) and I'd like to validate it analysing the Kaplan Meier survival curve. I had a look at the literature and most of the time this curve is calculated using the expression value of a single gene. The patients are divided in two groups: low expression and high expression, often using and arbitrary expression value threshold as the mean. Finally using those two group the curve is plotted. What is a common practice to do when the number of genes is higher than one? How the patients are assigned to the two groups?
Furthermore, is there a simple tool that allows me, given:
a) list of genes
b) expression values of those genes
c) survival information of the patients
to create/plot the Kaplan Meier curve?