Scared

The treatments for cancer are scaring me so much.  I don' t want my sister to have to do them.  But I know she does - I want her to live.  But then I see articles where they say they aren't that beneficial and do more harm than good!  What to do - I want my sister to live!  Of course it's her choice so I really can't do anything at all - except be there for her.  Will her lifetime be dramaticlly shorter even if she survives because of this?  I always thought she would live the longest...