There seems to be an Earthquake in cancer understanding coming. There's an idea that's been around since about 1930 that was promoted by a physician who won 1 nobel and almost won a 2nd nobel prize in medicine. Basic understanding of respiration was the nobel prize of 1934. (Otto Warburg).
I'll state all the following as if it is all known, factual, correct, and without qualifications to facilitate easy reading.
When a normal nucleus is inserted to replace a "cancerous" nucleus, the cells continue to multiply, keeping the good nucleus without modification. Inserting the nucleus from a cancer cell into any normal cell does not maintain the cancer. So cancer is not in the nucleus, the nucleus is just interacting with the rest of the cell, although obviously sometimes the nucleus is genetically biased towards certain cancers.
The mitochondria's ability to generate ATP can become impaired for some reason, like a toxin or a virus. Viruses target mitochondria DNA before the nucleus. Mitochondria also produce ROS for immunity defense. If enough mitochondria structures fall apart and if certain sufficient enzymes are present in the cell, cell death occurs. Also, based on a certain receptor, less dead mitochondria are needed to cause cell death. If there are not many mitochondria and they are not producing much ATP, they will not have a lot of the protein (cyt C) that initially signals cell death by this method. Muscles never get cancer ... supposedly partly because they are loaded with mitochondria that can more easily signal cell death when needed.
If the cell does not die from the above and the mitochondria are not producing sufficient ATP (or the needed enzymes are not present) for whatever reason such as stress, then "cancer-causing" genes in the nucleus (many of which are normal) are activated into action to produce proteins that will allow 2 other non-aerobic pathways to produce ATP. These are ancient anaerobic pathways that are much less efficient and use glucose and produce lactic acid. It is anaerobic fermentation to produce ATP. Muscles really know this pathway, or a variation on it, and apparently know how to deal with it.
Something occurs that causes the cell to multiply. If there is insufficient vit D3, which can be caused locally by a certain protein being released that converts it all, then new vessels can be formed to supply the cells. (although there are I suppose many other reasons angiogenesis can incorrectly occur).
So I have insufficient mitochondria (specifically cyt C) or certain enzymes, multiplication, and low vit D3 or an excess of one of its breakdown enzymes, all of which can be influenced by the nucleus, but it's not fair to say the nucleus is the cause if the mitochondria or the enzymes can be improved to overcome a virus, diet, or genetic bias.
Metastases are supposedly being cause by macrophages being released by the cell, which are allowed to spread by design in the body....ironically for purposes of killing other cells (immunity) or repairing. But you can see they have the technology inside them to be cancer if used incorrectly.
You can greatly slow the progression of a cancer by using a calorie-restricted ketogenic diet (no carbs) which allows the mitochondria to do their job with oxygen without GLUCOSE. No carb diets do not help unless it is calorie-restricted because fats and protein can be converted to glucose.
LED light therapy (red and near-infrared, 830 nm being preferred) kick-starts the mitochondria's to use OXYGEN to produce more ATP (via both glucose and ketones). This might activate signals to be sent that produce more mitochondria. Or if you over-supply the light it can produce ROS. So the combination of a ketogenic diet, hyperbaric oxygen, and LED light therapy, and a non-active glucose mimic to plug the anaerobic pathway, we might be getting close to effectively reversing many forms of cancer. Almost every phytochemical you can identify that has been studied at a weight of 1% or 2% of diet in mice and rats can slow cancer models about as much as the low-calorie diet. 50% slower progression for many. If you take any plant and isolate the 3 best cancer nutrients in it and give it 3% of diet without excess carbs, you better see the cancer slow by at least 30% or you did your study wrong. Paleolithic plants were much smaller and had much higher surface areas and much fewer carbs per nutrient.
Here is a video on the core of the ideas, by Thomas Seyfried. References to muscles, vitamin D3 as related to angiogenesis, and light therapy are from other sources.
"Excessive angiogenesis" diseases reads like a who's who list of insufficient vitamin D3. Cancer, Alzheimer's, psoriasis, inflammation, arthritis, etc.