In the book My Sister's Keeper a young girl hires a lawyer to stop from having to be used as replacement parts for her sister who is dying. Her mother had become impregnated with her in order to be able to save her sister. What was meant to be a one time fix has turned into a lifetime of transfusions and cell harvesting and other necessary treatments which involves her body.
The real clincher in the story is that the older sister is the one who had her sister get the lawyer. She is exhausted and wants it all to stop.
The theme of the story is sibling love and also parental love. Because the older sister can not take on the battle herself, her younger sister has to step up for her and challenge her parents in order to stop the treatments.
The parents would never stoop the treatments on their own because they fear losing their daughter.