Just being around is so much help, even though it may not seem it at the time. Also, when my mam had breast cancer 20 years ago, sense of humour was key. My mam found the hair loss from the chemo emotionally difficult but used to make jokes when she was out and about, things like passing a hairdresser and suggesting she go in for a wash and blow dry and imagining their faces when her wig fell off! It's a tough time for any family, keep talking together, laughing together and crying together. Keep life as normal as possible but make sure your sister is careful about exposure to germs during the chemo. One of the best tips my mam got was to suck on pineapple cubes to take away the bad taste from the chemo. Her nurse told her this and it worked for my mam, two of my friends and a friend of the family. Most of all, remember the excellent recovery rates! My mam is a testament to this and is still a picture of health 20 years on.