For advanced cancer patients deliberating early clinical trial participation, adequate information about expected effect on quality of life (HRQoL) and hope, may support decision making. The aim was to assess the potential relation of HRQoL to eligibility for phase-I trial participation, and to observe the variations in patient-reported outcomes. Patients completed questionnaires at preconsent (n = 124), baseline (n = 96), and after first evaluation of a phase-I trial (n = 76). The Mann-Whitney U test was used to test differences between eligible and ineligible patients. Univariate logistic regression was performed for eligibility. Factorial repeated-measures ANOVA compared the outcomes of patients continuing vs. stopping participation after first evaluation over time. Eligibility is associated with significant better global health OR = 0.946, 95% CI [0.918, 0.975], p = 0.001, physical functioning OR = 0.959, 95% CI [0.933, 0.985], p = 0.002, role functioning OR = 0.974, 95% CI [0.957, 0.991] and better appetite OR = 1.114 95% CI [1.035, 1.192]. HRQoL outcomes like global health, social functioning and appetite decline in all patients and differ between patients continuing or having to end participation. Over time, hope and tenacity decline in all patients and coping strategies alter in patients stopping participation. Trial participation influences patient-reported outcomes. Global health may predict for eligibility and trial continuation. Informing patients could affect patients' decision making.