Many people would be unable to walk away because they would feel they were less than they should be. well, lots of people experience lots of loneliness (no partner) and they aren't ill, so the two really aren't connected. I have a friend who was treated for breast cancer, and they have so many support groups and services and volunteers who will befriend and take care of people going thru treatment, and after treatment in support groups.
I know she is receiving top-notch care, and they say cancer is no longer the death sentence it use to be.
granted, she doesn't have to spill it on the first date, but after a few dates, she should have told you, if it is a serious enough case that she could well die within the next year or so.