data hepatit;
infile 'hepatit.txt' firstobs=2;
input months treat cens;
lmonths=log(months);
run;

proc lifetest plots=(s);
time months*cens(0);
strata treat;
run;

proc phreg;
model months*cens(0)=treat;
run;

proc genmod;
model cens=treat/dist=poi offset=lmonths;
run;