Stage 4 fibrosis is the first stage of cirrhosis. There are stages of cirrhosis, too, so don't think this is end stage liverdisease. Not by a long shot!
It is still a manageable disease and one in which, if you can tolerate it, six months of Pegasys and ribavirin is a very good idea.
Staying off the cigs is now a necessity and you have no time to waste. You cannot afford to risk further damage by smoking or postponing treatment any longer than it takes to get yourself ready.
