This is a cross-sectional, observational and correlational survey study.This study is aim to survey the the knowledge, attitudes, and decision making towards clinical trials in cancer patients in Taiwan (R.O.C.), which attempts to invite some cancer patients who have been experienced the treatment clinical trials' informed consent process. The research tool is a questionnaire which includes some scale: (1)Clinical trial Knowledge scale, (2) Attitude toward randomized clinical trials scale, (3) Shared Decision Making(SDM-Q-9),(4) Satisfaction with Decision (SWD-scale), and (5) Decision Regret scale(DRS). The investigators expect the research outcome can provide some instructions to improve patients' autonomy, satisfaction of the decision making and communication process between patients and Medical professors whenever cancer patients participating in clinical trials.