When dealing with the most serious issues in life such as cancer people should have a very wide berth in which to question and express, and your question is very appropriate.
I was not aware that she died of cancer, perhaps they tried to hide that inititally???
to answer your question:
I read her books circa 1999-ish. They were very popular in the alternative and new age book stores. Some of what she said struck me as common sense, for example clean all the crap out of your cupboards and drawers. get rid of all the poisonous body creams, soaps, cleaning agents, etc etc. Few people would disagree with that. It has since become almost a defacto rule of thumb now and the alternative organic cleaning and health care industry has boomed since then.
She also did some serious homework in revealing all the poisonous substances present in the food supply, exposing sources of heavy metals, solvents, plastics, etc etc. I don't think anyone can fault her for that. To the contrary she should have been given a medal.
Now in regards to parasites I think she went overboard. Not that parasites are not an endemic issue, they most likely are. But i think she missed the boat on the nutrition and detoxification side of things, and this is just speaking from personal experience. I don't think her detoxification skills were up to par. But, keep in mind this was over a decade ago before the internet really became the hub of information exchange that it is now. No one is perfect and has the ultimate answers for everyone. There are many flaws in her approach that i could come up with, but i don't really want to waste my time on that. People died in her clinics in mexico, but people die from all sorts of alternative therapies, and many of them were very sick.
All it took for me was to see her picture and I could tell she wasn't a healthy woman herself. This is purely subjective, but she didn't exude any vital energy in her pictures. When people start to profess to have big answers to health problems i usually like to look at them very carefully and listen to them very carefully. so personally I jsut took what she said with a grain of salt, but her books were extraordinary and she did shine a big light on problems like parasites and chemicals and dental fillings that needed to be exposed. She deserves credit for that as well.
At the end of the day i would say that parasites are a resultant problem, and rarely causative. she did say this in her books, but at the same time she devoted much too much energy to destroying worms and not enough to strengthening people's innate energy levels and her detoxifcation methods were less than what is needed for a lot of people.
i would liken her to a pioneer who had great information that is now being refined as we speak by people on curezone and the next generation of healers and thinkers.
and i would have to agree with you at the end of the day. when a person who writes a book on how to cure cancers dies of cancer, something is not right.