There are attitudes toward cancer and death that are drawn from another perspective. The concern is that by describing another person's life as "fighting cancer" we ascribe that perspective to the other person without respecting how that person actually views [or viewed] their life.
Life is much more than a fight. Even life with cancer. Take a look at Steve Jobs. His "fight" wasn't publicized (likely because that's what he preferred), but he did accomplish things while also living with cancer that were publicized.
Shouldn't it be the same for others who live with cancer?