To which my response is always, "And? My cancer doesn't make your flu any less unpleasant."
Flu, work issues, indigestion, divorce, health, life issues. Stuff happens to us. My life isn't yours, yours isn't mine, and whatever's up with you isn't any less important or troublesome just because I'm down inside the chemotherapy meat grinder.
It's something I hang on to, for my sense of normal. That everyone else's life goes on, good, bad and indifferent. My cancer doesn't devalue your experience. Your experience enhances mine. It's such a simple, difficult thing.