Anticipatory grief benefits from recognition and acknowledgement.
One phrase that names the experience you describe in your post "Thoughts on cancer" is anticipatory grieving. As human beings we, or at least some of us some of the time, are self conscious, and based on past experiences we know what lies ahead. Is this ability to anticipate future events a blessing or a curse or more likely a little of both?
Anticipating losses in the future based on our experiences of losses in the past, initiates an emotional process that most people aren't aware of or even if they are somewhat aware, they can't name it.
Colloquially, we sometimes in a dismissive way, say things like "Been there. Done that." And here we go again.
There are many other aspects of anticipatory grief that we can make note of like "disenfranchised grief" or what is sometimes also called "unattended sorrow." Anticipatory grief, not being recognized and acknowledged, is sequestered down in the psyche to be acted out in all kinds of ways, one of the most notable of which is somatization. It makes people physically sick.
What, then, is to be done with anticipatory grief? We need shoulders to cry on. We need people we can express it to who will understand and support us with their non anxious presence. I am blessed by the sharing of anticipatory grief. I think to myself, "You too?" It must be going around. I am reminded of the Beatles great song lyric, "I'll get by with a little help from my friends."
We are all in this thing we call "life" together and when we recognize and acknowledge the spark of the Divine in the other we join together in something that is holy.