Dr. Kelley cured himself of pancreatic cancer using high doses of enzymes, this was from the research of Dr. Beard who surmised that reduction of pancreatic enzymes enable tumors to form. These enzymes are able to erode the protective coat of the tumors to allow the immune system to attack.
Tumors are more than likely an immune response which sequesters pathogenic organisms (my opinion)
Have you had b12 levels checked since they are low in vegans? I suppose that your protein levels are adequate since this could be low in vegans?