You don't not treat the control group. You give the control group the current standard treatment, and you give the experimental group the new trial treatment.
You don't not treat the control group. You give the control group the current standard treatment, and you give the experimental group the new trial treatment.
In some cases, the "current standard treatment" is no treatment.
In some studies, although not cancer, I've seen treatment offered to both groups, someone in the control at any time can opt into the same treatment the other group receives if they want to. Some people will make the informed decision to not take the treatment, and they are your control.
No longer randomized though, so it brings in confounding factors. Which one then has to try to control for.
Doesn't really change your point, but I should clarify that what I said was wrong, it was anyone in the study could choose not to take the blinded pill that could be placebo or active, they were removed from the study, and were provided with the active experimental drug + compensation as to not punish them for giving or not giving their consent after being sufficiently informed of the risks of either choice.
Really? That sounds dumb and unethical. Is the standard treatment for a cut a bandage or leaving you to bleed?
If there is no treatment available, then yes, the standard treatment may be nothing, or possibly just trying to make the patient more comfortable until they die.