Fear for my mothers life.

To try and keep a long story as brief as possible, my Mum was sexually abused as a minor, only to go on and experience long periods of domestic violence all throughout her teenage years well into her early thirties, she uses recreational drugs and alcohol as a coping mechanism always has and always will, about 2 years ago she was diagnosed with Thyroid cancer, during the surgery for the removal of the cancer there were complications which has lead to further calcium problems which could ultimately lead to death [ hopefully this helps to understand her frame of mind ] back in November 2015 she tried to kill herself, she was taken to hospital by an ambulance then released only hours later, since then her mental state has just deteriorated, she's always had a drink problem, one she's never admitted to, she refuses to get help, and it seems the professionals wont intervene as they don't deem it "serious enough", she's not coming home from nights out, if she is it isn't till the early hours of the morning, my 17 year old brother is constantly worried sick about her, due to the drink and the drugs, and i just cant make her see sense. so in a nutshell that's about it.

any advice would be greatly appreciated.