Table 2.

Dimensions Identified through Exploratory Factor Analysis and Original Survey Items

Dimension	Original Survey Items
Promoters:
Physician personal benefits	▪Local trials keep patients in the community ▪Frequent contact with PI/researchers ▪Trial participation gives prestige ▪Frequent exposure to EPCT information
Trial treatment benefits	▪Possibility of therapeutic benefit to patient ▪Possibility that experimental treatment is better than standard treatment ▪Trial provides the best and most current treatment
Patient psychosocial benefits	▪Possibility of psychological benefit to patient ▪Patient/family wants to try something new ▪Comfortable explaining EPCTsa ▪Patients are followed very closelya
Logistical barriers:
Clinical trial process burden	▪Paperwork of referral process is too time-consuming ▪Too much time required to explain an EPCTs ▪Excessive details of protocols ▪No staff support available ▪Referral procedures are too complex ▪Referring patients to EPCTs is extra work
Coordination/Involvement with clinical trial site	▪Contacting the PI is too difficult ▪Contacting the referral office at CT site is too difficult ▪The institution does not keep me in the loop regarding my patients
Personal Barriers:
Personal/Attitudes	▪Don’t want to increase patient’s anxiety ▪Language barriers with minority patients ▪Patients will blame the referral oncologist for any adverse effects ▪Hassle of convincing patients to participate ▪Difficulty explaining medical uncertainty ▪Referring patients to trials might negatively affect relationship with patient ▪Distrust of researchers conducting the trial
Lack of personal benefits	▪Lack of rewards and recognition ▪Loss of personal income as a result of patients seeking treatment from trial physicians ▪Fear loss of control over patient care ▪Lack of awareness about EPCTsa
Protocol-Related Barriers
Protocol complexity	▪Misinterpretation of study protocol ▪Consent procedure too difficult or complex ▪Trial protocol too complex ▪Misinterpretation of eligibility of patients ▪Eligibility criteria too strict/stringent
Trial treatment	▪Toxicity/side effects of experimental TT outweighs possible benefits ▪Trial therapy not as good as standard therapy ▪Low probability of therapeutic benefit to the patient

^aStand-alone items not related to identified dimensions