Introduction: The use of complementary and alternative medicines (CAM) by oncology patients is a widespread practice generally outside of the main course of treatment. The lack of understanding between patient and professional perceptions can lead to deficient communication with negative effect on cancer care. Objective: to explore the perception of patients and caregivers, as well as coincidences and divergences regarding the use of CAM in cancer care. Methods: an exploratory study with interpretative phenomenological analysis was carried out. We used focus group with pre-established domains. Independent manual coding was performed and the codes subsequently grouped for interpretation. The grouping was triangulated with the research team to generate definitive categories. Results: Two categories emerged: conceptualization and life-experience with CAM. Each category includes similar (i.e. denominations, use of CAM) and differential subcategories (i.e. value judgment, scientific rationale), between the two groups. The conceptualization recognizes how participants characterize the CAMs and the life-experience identifies the way they relate to the CAMs. Conclusions: Patients and professionals share concerns regarding the use of CAM, but there are differences in language and expectations concerning its use. For patients, medical advice is relevant but not definitive and scientific evidence is only relevant for professionals.