Whatevergirl, I will be praying for your sister.
As someone that has colon cancer in the family, I know how your sister feels. My grandfather died from it, & my dad is a survivor.
Last year I had a stomach virus (I thought) & ended up w/ bloody stools. That was the first time I had that happen btw. First thought that popped into my head? I had cancer.
So I set up an appt. that Monday, got in, told dr. the family history with cancer & he set me up for a colonoscopy. So of course it was going to be 4 weeks before I got in and that whole time I was scared.
Well had the colonoscopy, & there was a polyp. Thank God it was benign. But the dr. did tell me that for my age (40) that if I had put off having the colonoscopy until I was 50, I’d be facing cancer. Now I do not know how old your sister is or how long she’s had symptoms, so maybe this will help or not.
But the dr. also said I had diverticulosis. That’s what I thought was the stomach virus. Diverticulosis is weak spots in your colon. Picture an inner tube that has those weak spots that kind of bulge when inflated? Nuts, seeds, hulls etc. get lodged in your colon & cause infection. And it just so happened the Friday before I got sick I kind of o.d.'d on popcorn.
Now the colonoscopy was a breeze. The worse part was the prep work. I had to drink this stuff that cleans your colon out. Just tell your sister to be by the toilet once she starts. And also, I know this is graphic stuff, but this was what my dr. told me to do & this is verbatim

: lather your cheeks well with vaseline & use baby wipes/tucks pads instead of toilet paper. Another thing the dr. told me was that once I was cleaned out from drinking that solution that I didn’t have to drink the whole gallon. That’s how it comes, in gallon jugs. I think I ended up drinking about 3 quarts. My dad said he wished his dr. gave him the same advice.
Everyone should have a colonoscopy by the time they’re 50, earlier if cancer runs in the family. I cannot stress that enough. Also get in a minimum of 20 grams (work up to 25-30 gm) a day of fiber. Fiber is the #1 thing we can take in to help avoid or at least minimize our chances of getting this cancer.
I hope that maybe some of this had helped. God bless & prayers are going to your sister whatevergirl! I’m sure things will be fine.