There is one main reason for this as far as I can see.
Many people mistakenly support the American Cancer Society which is very ingnorant about the importants of nutrition and supplements in fighting cancer and they are in fact, very very anti-alternative. You can read this in their literature and they are blatantly anti-alternative.
The group that supports alternatives and nutrition in cancer research is the American Institute for Cancer Research ( AICR ). You can contact them and request a list of supported projects. They do not fund chemo-therapy research.
The NCI, ACS, etc support the pharmaceutical companies and by supporting them, you are wasting your money because it does not go to cancer research, it goes to drug research.