Worried for mum's future

Hi everyone, 

My mum was diagnosed with Stage 4 Bowel Cancer and Secondary Liver cancer, around two months ago. She was due to start Chemotherapy last week but the day before was called to say that the oncologist wasn't happy to start due to an ongoing UTI mum has had for several weeks despite multiple antibiotics. The plan was for the oncologist to see her later this week, have a PICC line put in and start treatment the next day. Mum then decided last week that she needed to see a dentist about a problem she has had with a tooth for over a year. It's now looking likely that she'll need a tooth removing which means a further delay to treatment. My worry is that, mum has been very open in admitting she is terrified of the treatment and I can't help thinking she's possibly deliberately delaying treatment by having the dental treatment. She has already talked about not continuing if the treatment is too much. I feel utterly helpless. I know I have to respect whatever decision she makes but am so scared she's not even going to try the treatment. My aunt passed away a week and a half ago from breast cancer which had spread so we are going through a difficult time. My thoughts are completely running away with me. The person I'd normally turn to when I have worries is my mum and I can't do that.