Aren’t clinical trials for cancer treatment really just for advanced stages of cancer when no other treatments are available?

Is it really true that participants in clinical trials for cancer treatment are often treated like guinea pigs?

Aren’t clinical trials for cancer treatment dangerous because they use new medicines?

Is it true that I’ll only get a placebo if I participate in a clinical trial for cancer treatment?

Is it true that if I enroll in a clinical trial for cancer treatment, I’ll be locked in and won’t be able to change treatment?