First and foremost, this video: https://www.youtube.com/watch?v=SEE-oU8_NSU explains the metabolic state of cancer cells, from the fermentation of glucose, which you already know is a major factor in cancer and is in my post in the portion above (I can bring it down here if you need to see it), to the Warburg effect.
"The reason that acidity is seen as an issue is because while healthy cells get the majority of their energy from oxygen respiration, cancerous cells tend to inefficiently use glucose at a higher rate than healthy cells. This consumption of glucose (a process called glycolysis) results in acidic waste products, and consequently a higher acidity around cells which use this mechanism. This increased reliance of cancer cells on glucose even when there’s enough oxygen is known as the Warburg effect." ~Ergo, cancer causes the acidic environment around it through glycolysis, the fermentation of glucose in the cell. That is explained earlier in the video.
One important thing to take note of is that the alkaline diet is most definitely not Ketogenic, and is vegan in nature; this is the common one that most websites use as their basis:
Acidic: Meat, poultry, fish, dairy, eggs, grains and alcohol.
Neutral: Natural fats, starches and sugars.
Alkaline: Fruits, nuts, legumes and vegetables.
Now, I usually do not post Snopes because they aren't a scientific site, but they did post science I will place under the article and have a good explanation and even links to the site of the man who made up that nonsense. His name was 'David “Avocado” Wolfe'.
Everyone Who Has Cancer Has a pH That Is Too Acidic
~The results were false, and science explains why. The site, itself is not a scientific reference so please know I am not claiming it is.
Nutritional disturbance in acid–base balance and osteoporosis: a hypothesis that disregards the essential homeostatic role of the kidney
~This study, for one, shows that in order for blood to be overly acidic, one would have to not have kidneys. Other important PH-balancing organs which would need to not exist are the liver and lungs.
Potential renal acid load of foods and its influence on urine pH.
~This study explains that diet affects urinary PH. Beyond that, it pretty much has nothing to do with your blood or tissue PH, which is controlled tightly by your lungs, kidneys, and liver--if we were able to alter that in any way with diet beyond a fraction, we would die, period.
Cancer Cell Metabolism: Warburg and Beyond
~An explanation as to how cancer metabolism works.
THE METABOLISM OF TUMORS IN THE BODY.
[In every case, the veins contain more lactic acid than the arteries, hence in every case lactic acid is formed as the blood passes through the tumor.]
"That means, by his model, that both the acidity and the low oxygen would be a symptom, not a cause. It also bears highlighting that Warburg is talking about the pH of blood in veins and arteries here, which, as discussed above, cannot be modified by diet."
The kidney and acid-base regulation
Liver regulation of acid-base balance.
These two studies show that not only do cells become more invasive with acidity rise, it's caused by the cancer, themselves, and is a part of the cancer metabolism, not because of bodily PH. That metabolic state of acidity is an isolated pathway not affected by dietary factors.
Acidic pH enhances the invasive behavior of human melanoma cells.
Acid treatment of melanoma cells selects for invasive phenotypes.
[Solid tumors become acidic due to hypoxia and upregulated glycolysis. We have hypothesized that this acidosis leads to more aggressive invasive behavior during carcinogenesis (Nature Reviews Cancer 4:891-899, 2004). Previous work on this subject has shown mixed results. While some have observed an induction of metastasis and invasion with acid treatments, others have not.] ~This concludes that further, it's not even solid evidence because while it happened in some, it didn't happen in others. It was more along the lines that acid actually destroyed weaker cells and the more aggressive ones were able to survive. Thus it's not actually a case of "acid makes it more invasive", it's a case of the acid killing off the weaker cells and the invasive ones proliferating because they have no competition.
Now, with all of that research above, it can be simply explained by this doctor; no, I don't like quackwatch--this man just explains everything in a comprehensive article which can be verified by biology texts and the above information--I'm working on my own article on my site for this group:
Acid/Alkaline Theory of Disease Is Nonsense