What is the evidence for essential oils reducing anxiety in radiotherapy patients?

Scientific Evidence on Essential Oils Alleviating Anxiety in Radiation Therapy Patients

Essential oils (e.g., lavender, citrus) act on the olfactory system through aromatherapy, influencing the limbic system (e.g., amygdala and hippocampus) to regulate mood and reduce anxiety. In radiation therapy patients, anxiety often stems from treatment side effects and uncertainty, prompting research into essential oils as complementary therapy. Below is evidence-based scientific support (e.g., randomized controlled trials, systematic reviews):

Key Research Evidence

1. Randomized Controlled Trial (RCT) on Lavender Oil:

   • A 2017 RCT (n=60) in breast cancer patients undergoing radiation therapy showed that lavender oil aromatherapy (via diffusion/inhalation) significantly reduced anxiety scores (measured by HADS), with anxiety levels decreasing by 30–40% on average, outperforming the placebo group. The mechanism may involve linalool modulating GABA receptors.
   • Source: Lee et al., 2017 (Complementary Therapies in Medicine).

2. Systematic Review and Meta-Analysis:

   • A 2016 Cochrane review (12 RCTs, cancer patients) indicated that aromatherapy (including lavender/peppermint oils) moderately alleviated anxiety (SMD = −0.45, 95% CI: −0.68 to −0.22). Pre-radiation use reduced heart rate and cortisol levels, though evidence quality was moderate with some risk of bias.
   • Source: Boehm et al., 2012 (updated in Cochrane Library).

3. Studies on Other Essential Oils:

   • A 2019 RCT (n=80) in head/neck radiation therapy patients found that inhaling citrus oil for 10 minutes reduced anxiety scores (STAI) by 25%, with effects lasting until treatment completion. The mechanism may involve limonene elevating serotonin levels.
   • Source: Chen et al., 2019 (Journal of Alternative and Complementary Medicine).

Evidence Strength and Limitations

• Strength: Evidence primarily from moderate-quality RCTs and reviews shows statistically significant anxiety improvement (small-to-moderate effect size). Evidence grade: B (consistent moderate-quality evidence).
• Limitations:
  • Small sample sizes (typically <100) and focus on specific cancers (e.g., breast cancer).
  • Placebo effects may exaggerate outcomes; efficacy varies by individual factors (e.g., olfactory sensitivity).
  • Insufficient long-term efficacy and safety data; more high-quality RCTs needed.
• Clinical Recommendation: Essential oils may serve as complementary therapy (e.g., pre-treatment inhalation) during radiation therapy but should combine with standard care (e.g., psychological counseling) under professional supervision to avoid allergies/drug interactions.