If you try a treatment and you die 8 months later, it could be that:
a. The treatment's generally effective but not in all cases. You just happen to be the exception.
b. You might have been cured if you hadn't waited so long to start that treatment.
c. Without the treatment, you would have died 2 months later.
d. Without the treatment, you'd have lived just as long, but you felt better during those last 8 months because of the treatment.
e. You didn't follow the instructions.

Etc.