From what I’ve read, you’re probably right. There is some break down in healthy cells, whether it’s genetic or life exposure. They can sit like that for quite a while or never get triggered. But the health of our cellular makeup throughout our body sets up a situation where a damaged cell starts to reproduce. Stress, inflammation, new exposures to carcinogens, hormone imbalance, oxidative stress, and more can mean our cells are not healthy enough to fight.
My stress level was through the roof in those 4-5 years before my DCIS was visible in an ultrasound. I had an intermediate grade nuclear level which evidently can take about 6 years to grow from a cell to about 2 cm.
This was work related stress - but it affected everything in my body. I also had a 9% weight change, lost then regained during that time so my ER+ cancer was no doubt affected by the changes in estrogen and fat.
It seems that researchers are spending more time looking at the makeup of the surrounding parenchyma or cells around the cancer to figure out why some cancers move out into the surrounding area (then move in to blood or lymph system). Some cellular makeup is more friendly to cancer growth. Cells with a healthy homeostasis deter cancer growth.
Anyway, that’s my simplified take on what I’ve been reading,

We all know of incredibly healthy people who get cancer - so it’s not always unhealthy cells fueling cancer to grow. It’s part of being human, although I wish it weren’t so.