An Essential Oil Intervention for Chemotherapy-Induced Peripheral Neuropathy in Breast Cancer Survivors: A Mixed Methods Study

Abstract

Chemotherapy-induced peripheral neuropathy (CIPN) is a painful, debilitating consequence of cancer treatment and is considered the most adverse of non-hematologic events. Pharmacological approaches to CIPN are often ineffective and cause adverse effects. A problem faced by many breast cancer survivors is poor CIPN treatment coupled with practitioners’ lack of understanding about their subsequent quality-of-life (QOL). Essential oils (EOs) are an underutilized non-pharmacological approach to pain reduction. EO mechanisms of action include non-competing inhibition of 5-HT, AchE, and Substance P and antagonism of TRPA1 and TRPV1. The study aims were to ascertain the effect of an EO intervention (EOI) on CIPN and quality-of-life (QOL) in breast cancer survivors and develop a deeper understanding of CIPN QOL using photovoice methodology. This mixed methods research design employed a randomized, single-blind, placebo-controlled trial. Twenty-six breast cancer survivors with chronic lower extremity CIPN were enrolled in the quantitative strand using purposive sampling. Participants were stratified by baseline pain score and randomized to intervention (n = 13) and placebo (n = 13) groups. Participants topically applied an EOI (containing Curcuma longa, Piper nigrum, Pelargonium asperum, Zingiber officinale, Mentha x piperita, and Rosmarinus officinalis ct. cineole) or placebo three times a day for six weeks. Pain was assessed weekly using the Short-Form McGill Pain Questionnaire-2 (SF-MPQ-2) and daily using the Visual Analogue Scale (VAS). QOL was assessed using the QOL:CIPN20 and QOL Adult Cancer Survivor questionnaires(QLACS) at baseline, midpoint, and endpoint. Data were analyzed in SPSS using generalized estimating equations. Test of model main effects were significant for visit (SF-MPQ-2, p = .000; VAS, p = .008; QLACS Pain subdomain, p = .026), but not for visit*group interaction effects. SF-MPQ-2 and VAS positively correlated with QOL:CIPN20 scores (r = .843, r = .671); however, QOL:CIPN20 model main effects were not significant. The VAS %Δ for intervention and placebo groups was -14.67 and -7.57 respectively. This was not statistically significant, but is clinically important. Regardless of group assignment, pain and QOL improved. The EOI was well-tolerated and demonstrated 50% more pain reduction than placebo. A subset of participants(n = 9) were enrolled in the qualitative strand, received photovoice-related training, and spent four weeks photographing their life with CIPN. Participants participated in photo-interviewing, a photo discussion focus group, a photovoice exhibition at a local art gallery, and an event de-briefing focus group. Data were analyzed in NVivo using thematic, visual content, and iconographical analyses. Six primary themes emerged from the data: (a) advice for clinicians, (b) positive photovoice experience, and CIPN (c) causes pain, (d) affects relationships, (e) causes disruptions, and (f) alters self-image. Further research is needed to enhance EO pain-reducing efficacy as a natural nursing intervention. CIPN greatly impacts breast cancer survivors’ QOL and is multifaceted. Nursing care for breast cancer survivors should include education regarding the potential severity and lifelong effects of CIPN and benefits of study participation and group support.