BACKGROUND: Nondisclosure of a poor prognosis to patients with advanced cancer remains a typical practice in Asia. Although the importance of prognostic communication has increasingly been recognized worldwide, little is known about whether explicit prognostic disclosure positively affects Asian patients with advanced cancer. The objective of this study was to examine the effects of explicit prognostic communication on patients with cancer recurrence. METHODS: In this randomized, video-vignette study, Japanese women with breast cancer who had undergone curative surgery viewed videos of prognostic communication between a patient with recurrent, incurable breast cancer and her oncologist. The videos differed only in the presence or absence of explicit prognostic disclosure. The primary outcome was participants' uncertainty (rated from 0 to 10), and the secondary outcomes included anxiety (measured on the State-Trait Anxiety Inventory-State: range, 20-80), satisfaction (Patient Satisfaction Questionnaire; range 0-10), self-efficacy (range, 0-10), and willingness to discuss advance care planning (range, 1-4). RESULTS: In total, 105 women participated (mean ± SD age, 53.8 ± 8.2 years). After viewing the video with more versus less explicit disclosure, participants showed significantly lower uncertainty (mean ± SE scores, 5.3 ±0.2 vs 5.7 ± 0.2, respectively; P = .032) and higher satisfaction (5.6 ± 0.2 vs 5.2 ± 0.2, respectively; P = .010) without increasing anxiety (changes in scores on the State-Trait Anxiety Inventory-State: 0.06 ± 0.5 vs 0.6 ± 0.5, respectively; P = .198). No significant differences were observed in self-efficacy (5.2 ± 0.2 vs 5.0 ± 0.2, respectively; P = .277) or willingness to discuss advance care planning (2.7 ± 0.1 vs 2.7 ± 0.1, respectively; P = .240). CONCLUSIONS: Explicit prognostic disclosure prompted better outcomes than nondisclosure in Japanese women with breast cancer. When asked about the prognosis by Asian patients with cancer, clinicians may be encouraged to respect their wishes and explicitly discuss the prognosis if deemed appropriate. Cancer 2019;125:3320-3329.