Complementary and alternative medicine (CAM) is increasingly present in oncology, challenging the boundaries of conventional practice and raising important bioethical issues. This cross-sectional study investigated perceptions of the therapeutic value of CAM among 832 participants: 411 oncology patients and 421 healthcare professionals at a Croatian university hospital. Using validated CHBQ and IMAQ instruments, the results showed that patients’ expectations were significantly higher than those of physicians (p<0.001), particularly regarding psychophysical well-being (72.1%), immune system support (89.8%), and reduction of side effects (82.9%). Nurses occupied a middle position. These discrepancies reflect empirical differences and deeper ethical tensions between clinical authority and patient autonomy. CAM is a space where patients assert agency, seek meaning, and strive for holistic healing beyond biomedical reductionism. The findings underscore the need for ethical integration of evidence-based CAM into oncology care, supported by improved education and respectful dialogue. Supporting informed decision-making requires bridging epistemological gaps while respecting patients’ values.