The movie is "An Officer and a Gentleman" from the early 1980s. The actress (and love interest of Richard Gere) was Debra Winger.
She had several other major roles in movies. At least two (I think there are more) where she died of cancer. "Terms of Endearment" with Shirley McClain and Jack Nicholson and "Shadowlands" with Anthony Hopkins as C.S. Lewis.
She does die well...
Hmm, "dying well" is not an accomplishment I'd list on my resume...
OK, I wasn't sure who she was, but I've seen "Shadowlands". That's an excellent movie, though I haven't seen it in a few years. Since Mom's passing, I don't think I could handle it. Not yet. Too close to reality for me.