A method of cancer intervention or eradication by administering an effective amount of an endogenous ligand for the aryl hydrocarbon (Ah) receptor (AhR) named ITE or one of its analogs (the active ingredient) to a subject with cancer is disclosed. An effective dose and dosing frequency of the active ingredient are determined by measuring its blood levels of the subject after dosing. The active ingredient formulated with a carrier system is applied topically, enterally, or parenterally to the subject. The formulated drug can also be administered together with one or more of other cancer therapeutic agents. A maintenance dosing is provided after the subject is free of cancer to insure the cancer eradication. Subjects with cancers of prostate, liver, lung, ovarian, and breast are preferably accepted for treatment.