I take all offers of help from non-insensitive friends and family. I like to give my caretaker husband a break when possible so he can get out of the house and do fun stuff. I've also been given great wigs, beautiful scarves, etc.
Unhelpful comments include:
1) Stories about cancers not personally experienced in some way by the speaker, as patient, caregiver. or direct witness. Valid tips based upon same for dealing with cancer and chemo are great. No bummer hearsay cancer stories about distant cousins you have no relationship with. If it would be inadmissible for you to testify to in a court of law, zip it.
2) Comments like: "It was your choice to buzz your [remaining] hair." "You always had the best hair and now we have no reason to be jealous." "We're all having problems; I can't find a competent tile installer for my second home." It's great way to weed your friend garden, one of those gifts in disguise.
3) Time seems more precious to me since my cancer diagnosis. I have freed myself to say "no" ASAP to persistent unhelpful advisors, oxygen pirates, emotional vampires, professional victims, and unwanted time burners of all kinds. It feels great. Free at last!