Background: Adolescents and young adults (AYAs) with cancer generally want to engage in decision-making but are not always able to do so. We evaluated cancer treatment decision-making among AYAs, including decisional engagement and regret.

Methods: We surveyed 203 AYA patients with cancer aged 15 to 29 (response rate 74%) treated at a large academic center and their oncologists. Patients were approached within 6 weeks of diagnosis and asked to report decision-making preferences and experiences (Decisional Roles Scale) and the extent to which they regretted their initial treatment decision (Decisional Regret Scale) assessed at baseline and 4 and 12 months later.

Results: A majority of AYAs (58%) wanted to share responsibility for decision-making with oncologists; half (51%) preferred limited involvement from parents. Although most AYAs held roles they preferred, those who did not reported holding more passive roles relative to oncologists (P < .0001) and parents (P = .002) than they desired. Nearly one-quarter of patients (24%; 47 of 195) experienced regret about initial cancer treatment decisions at baseline, with similar rates at 4 (23%) and 12 (19%) months. In a multivariable model adjusted for age, decisional roles were not associated with regret; instead, regret was less likely among patients who trusted oncologists completely (odds ratio 0.17 [95% confidence interval 0.06-0.46]; P < .001) and who reported that oncologists understood what was important to them when treatment started (odds ratio 0.13 [95% confidence interval 0.04-0.42]; P < .001).

Conclusions: Nearly one-fourth of AYA patients expressed regret about initial treatment decisions. Although some AYAs have unmet needs for decisional engagement, attributes of the patient-oncologist relationship, including trust and mutual understanding, may be most protective against regret.