You are absolutely correct. Many do not understand that in certain cases, such as advanced cancer cases, certain herbs can interfere with treatments.
This is a reason why when you have advanced cancer it is more prudent to have a practitioner that has expertise in dealing with advanced cancer guiding you and monitoring you. Many want to do treatments on their own with herbs and supplements, but too often I see such cases worsen and only on the eleventh hour do the ask for help. Life is short but is is precious and priceless. Use herbs for early stages but for advanced stages seek help and use protocol that has proven treatments for advanced and advancing cancer.