Why doesn’t my doctor know about these treatments

The reason alternative cancer treatments are not more widely known has little to do with their alleged therapeutic ineffectiveness and far more to do with political control and the therapy marketplace.
Many of the treatments are on the "Unproven methods of cancer management" list maintained by the American Cancer Society, which is effectively a 'blacklist'. Also, your doctor will not know about most of these treatments because:
Medical schools don't teach alternative treatments.
Medical journals rarely contain articles about alternative treatments. Medical journals are published for the allopathic establishment, and they are mostly financed by advertisements from pharmaceutical companies.
Doctors receive a lot of negative information about alternative treatments from the American Medical Association (AMA) and the pharmaceutical industry.
Internet 'Quackwatches' and so forth decry alternative therapies even when there is contradictory evidence to their effectiveness. See Quackwatch below.
The American Cancer Society (ACS), the National Cancer Institute (NCI) and other Government cancer bodies will not investigate or promote alternative treatments.
Your doctor can only prescribe treatments that are Food and Drug Administration (FDA) approved. If your doctor prescribes treatments that are not FDA approved, he or she can be sued or lose their license.
Their state medical boards may fine them heavily, suspend their license to practice or even revoke it.
The federal government can close them down and confiscate their property.
They may lose their right to see patients in hospitals.
Others doctors (their peers) openly ridicule and criticize them.