"It takes some cancers up to eight years to gain a foothold and develope to the size of a pinhead in people who otherwise appear healthy."
That is one of the greatest myths about cancer!
I've already known several cases of people where the cancer developed suddenly, my own mother for instance. Because of her history with breasts cysts and her age she was religious with her check-ups but right when her own brother was dying of cancer and only months from her last mammogram she developed a big lump that was said to be stage II and which puzzled her doctor. Within two years she had metastasized to the lungs and brain and possibly the liver, I can't remember well. My godfather died of liver cancer not even a year after he had a bad car accident where he injured it, and so on. The really progressive doctors don't even believe that old school dogma anymore, but some are too blind to the evidence, they just stick to some belief only because it's comfortable and reject something unconventional because accepting it would disrupt their entire belief system.