I'm no expert, but I know cancer cells promote adding blood pathways towards them, so it might be that they have an "uneven share" of the nutrients transported to them, and thus die out later than the healthy tissue.
I don't know anything about cells going dormant as a result of fasting. That sounds questionable to me. There's been some research on fasting and cancer, but there haven't been a lot of studies, and results are inconclusive. Some of the ideas sound sensible. Cancer cells are incredibly greedy and slurp up glucose as they constantly divide. The thinking is that you can starve them and slow progression, in conjunction with chemotherapy and other treatments. It's not widely supported or practiced and more study is warranted. It's hard to find real information on it, because the idea that you can miraculously cure cancer and other diseases by changes in diet is embraced by millions of anti-science crackpots, so there's a ton of disinformation and speculation out there.
It's kind of the same idea as chemo. (Non-selective cell stress/death)
But won't cancer cells always starve first, as they don't have a way to go dormant?
Or is that a myth?