Abstract
Complementary therapies are increasingly integrated into the framework of integrative oncology. While numerous complementary therapies provide potential benefits, some may also carry risks, including interactions with conventional cancer treatments. The degree to which oncologists' real-world decisions regarding complementary therapies align with evidence-based guidelines remains uncertain. This study aimed to evaluate oncologists' evidence-based decisions on whether specific complementary therapies should be prohibited, permitted, or recommended for early breast cancer treatment. We conducted a cross-sectional online survey that included a randomized vignette experiment involving oncology specialists and residents from seven Southeast European countries. The primary outcome was the percentage of accurate classifications of 28 therapy-indication pairs in neoadjuvant and adjuvant settings, benchmarked against published evidence. Correctness was assessed using both a strict definition (one correct option) and an expanded definition (accepting "allow" or "recommend" when supported by evidence). A total of 136 respondents met the inclusion criteria and provided paired responses. Median accuracy was found to be 52% (95% CI 48-55) under the strict definition and 70% (95% CI 67-72) under the expanded definition, with no significant differences observed between neoadjuvant and adjuvant settings. Evidence-based therapies, such as physical exercise and cognitive behavioral therapy, were most frequently recommended, whereas most other therapies received endorsement from fewer than 25% of respondents. Overall, oncologists exhibited moderate alignment with evidence, demonstrating a tendency to permit rather than actively recommend complementary therapies, even when evidence indicated potential benefits and safety. These findings underscore the necessity for targeted educational interventions aimed at enhancing oncologists' understanding and ensuring the safe and informed integration of complementary therapies into clinical practice.