Update
We're going to the hospital later today to have my sister's staples removed. She'll then meet with her surgeon. When enough time has passed since her surgery, she'll have a few different tests for cancer based on different parts of her body.
After her initial shock and her putting aside the seriousness of her condition, her mood visibly dropped. She's worried about losing her job, and she got her financial matters in order. She spends a lot of time at home, by herself, so I give her my time whenever I'm there. I encourage her to talk about what's going on with her, knowing that she doesn't want to burden me with her troubles. I mostly listen.
In my original OP, I commented on my concern for my sister's drinking habits prior to her surgery. I asked her the other day whether or not she had thoughts about drinking or had cravings for wine. She said, "not at all," and I've seen no evidence to contradict this.
As I wrote earlier, my sister rarely went to see a doctor, and hadn't had a physical in years. As the years went by, she suspected that "something was wrong" the more she avoided getting checked out. Her smoking and more recent near-daily drinking only made her anxiety much worse. She couldn't even bring herself to talk about getting a physical.
I've been doing what I've been doing for a very long time. In terms of medical problems (and perhaps many other things in life), when you don't know, your anxiety is generally out of control, and this adversely influences virtually every part of your life. (As with drinking, we continue to drink because of our anxieties around the problems that drinking brings, only making things worse.) When you do know, anxiety subsides or at least is transferred to something tangible, something that can be treated. You then have an opportunity to channel all that wasted fear, the wasted energy, by doing the things that are necessary to heal. Some people here might call this "acceptance."