Since I see that there are some questions here about what a chemotherapy drug is, I've decided to do some extensive research in the hopes that I may offer some illumination on the subject. Here is what I've found thus far.
Chemotherapy drugs includes drugs that have cell killing, growth inhibiting agents. These drugs can be used alone or in conjunction with other drugs in the treatment of cancer
Now, I think that there may be some confusion between the terms "Chemotherapy" and "Chemotherapy Drugs" Chemotherapy is the treatment of an ailment (not limited to cancer) using chemicals that kill micro-organisms or (in the case of cancer) cancerous cells. Most commonly, chemicals used chemotherapy treatment act by killing cells that divide rapidly, one of the main properties of most cancer cells. Chemotherapy treatment generally refers to using antineoplastic drugs (cancer chemotherapy drugs, cytotoxic drugs). The drugs used in chemotherapy treatment to treat cancer are usually the combination of these drugs into a cytotoxic standardized treatment regimen (A fundamental principle of combination cancer therapy is that different drugs work through different cytotoxic mechanisms. Because they have different dose-limiting adverse effects, they can be given together at full doses in chemotherapy regimens).
In its non-onoclogical (non tumor, non mass, non cancerous) use, the term, chemotherapy treatment, may also refer to using antibiotics (antibacterial chemotherapy). In that sense, the first modern chemotherapeutic treatment employed an agent known as arsphenamine, an arsenic compound discovered in 1909 and used to treat syphilis. This was later followed by sulfonamides (sulfa drugs) and penicillin.
Chemotherapy Drugs: There are more than 100 drugs that are used today for chemotherapy treatment -- either alone or in combination with other drugs or treatments. These drugs vary widely in their chemical composition, how they are taken, their usefulness in treating specific forms of cancer, and their side effects. Chemotherapy Drugs are divided into groups - alkylating agents, nitrosoureas, antimetabolites, anthracyclines, topoisomerase inhibitors and mitotic inhibitors. Some drugs that we know here as immunosuppressant drugs, corticosteroid drugs, and some NSAIDs can be found in some of the classifications above. However, the drugs in those categories where we find our drug treatments for Lupus etc, are only listed in chemotherapy drugs because they are used in conjunction with the cell killing drugs as part of a chemotherapy cytotoxic standardized treatment regimin and, yes, many of them are synthetic (man-made) chemical agents.
Prednisone and Prednilosone are sometimes used in conjunction with cell killing drugs and, therefore, are sometimes included in the list of chemotherapy drugs and are used as a part of a chemotherapy treatment regimen. These two drugs are also synthetic drugs. However, it is important to note that not all synthetic drugs are used for chemotherapy treatment. Synthetic drugs are those substances that are produced entirely from chemical reactions in a laboratory. Their chemical structure can be identical to naturally occurring drugs, such as steroids, cocaine and opium, but they are often designed to enhance effects from naturally occurring drugs, or to prevent side effects from naturally occurring drugs that are unwanted. Many purely synthetic compounds with no alternative natural source are classified by the chemical structure of the parent synthetic compound. Drugs that share a common core structure belong to a particular group. But members within a particular group may produce different effects.
So, in a sense, both sides of this conversation are correct, with provisos, of course
Please let me know if I have been able to clarify this subject or if more research and/or information is needed.
Peace and Blessings