The Mid-Term Impact of a Hedonic Aroma on Psychophysiological Indicators in Women With Breast Cancer Undergoing Chemotherapy: A Randomized Controlled Trial

The study investigated the impact of essential oils on women undergoing chemotherapy (CT) treatment for breast cancer (BC), comparing an experimental group (EG) exposed to hedonic aromas with a control group (CG) receiving standard CT. A total of 112 women were randomly assigned to either a control group receiving standard chemotherapy treatment or an experimental group receiving an additional essential oil intervention during two consecutive chemotherapy cycles. The primary outcomes were quality of life (QoL), anxiety, and depression whereas the secondary outcomes were emotional distress, need for help, treatment beliefs, treatment side effects, illness perceptions, self-efficacy for coping, working memory, and cortisol. Mixed-effects models were used to analyse the differences between the two groups over time, more precisely, from the first CT session involving essential oils (T1) to two sessions later (T3), with a 6-week interval. Although no significant between-group differences were found for the primary outcomes, variations emerged in the patterns of association between these measures and several secondary outcomes over time. Specifically, in the EG, the association between baseline and subsequent anxiety remained stable, whereas this link weakened in the control group (CG). At T3, the adverse impact of higher anxiety on QoL and chemotherapy necessity beliefs was weaker or absent in the EG compared to the CG. Physiologically, higher pre-session salivary cortisol at T3 was linked to better QoL only in the EG, suggesting a normative acute stress response, whereas the CG showed attenuated reactivity. Other secondary outcomes, such as cognitive function and treatment side effects, did not differ significantly between groups. These findings suggest that essential oil inhalation may help stabilise anxiety levels associated with chemotherapy and contribute to QoL. These findings have relevant clinical implications.