Potential Mechanisms

Numerous in vitro studies have demonstrated that many different chemical constituents of multiple EOs have anticancer properties across cancer cell types including cytotoxicity, decreased cell viability, and growth inhibition.1 Some studies have suggested different mechanisms that drive these properties. Some EOs or constituents cause cell cycle arrest at various checkpoints, including Pallines spinosa (blackthorn) at the G0/G1 checkpoint and Capparis spinosa L. (caper) at the G2/M checkpoint,1,7 whereas others induce apoptosis through caspase-dependent pathways or reactive oxygen species, such as frankincense (Boswellia serrata), key lime (Citrus aurantiifolia), sweet lime (Citrus limettioides), Artemisia lavandulaefolia, clove (Eugenia caryophyllata), prickly ash (Zanthoxylum schinifolium), and balsam fir (Abies balsamea), and geraniol (a constituent of rose, palmarosa, and some citronella EOs).1,8,9 

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Some studies demonstrated that some EOs or their constituents increase sensitivity of cancer cells to chemotherapy, such as sesquiterpenes from Myrica rubra acting synergistically with doxorubicin against ovarian and lymphoblast cancer cells, and geraniol acting synergistically with 5-fluorouracil.1,10 Many chemical constituents modulate signaling pathways such as downregulating PI3K/Akt/mTOR, MAPK/ERK, or VEGF, as well as upregulating caspase-dependent signaling factors involved in apoptosis.1

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Conclusions

A substantial amount of in vitro data and some data from animal studies indicate that many EOs may have anticancer properties, primarily by causing cytotoxicity through caspase-dependent apoptosis, among other mechanisms. There are currently no in-human studies that have evaluated EOs through oral, topical, or inhaled administration for the treatment of cancer. It is therefore unknown whether the findings from these in vitro or animal studies will translate to humans.

Several small human studies suggest that EOs may be effective in supportive care, such as helping manage chemotherapy-induced nausea or radiation-induced toxicities. Large confirmatory trials, however, are needed to confirm these effects.

References

  1. Gautam N, Mantha AK, Mittal S. Essential oils and their constituents as anticancer agents: a mechanistic view. BioMed Res Int. 2014;154106. doi: 10.1155/2014/154106
  2. Halm MA, Baker C, Harshe V. Effect of an essential oil mixture on skin reactions in women undergoing radiotherapy for breast cancer. J Holistic Nurs. 2014;32:290-303. doi: 10.1177/0898010114527184
  3. Maddocks-Jennings W, Wilkinson JM, Cavanagh HM, Shillington D. Evaluating the effects of the essential oils Leptospermum scoparium (manuka) and Kunzea ericoides (kanuka) on radiotherapy induced mucositis: a randomized, placebo controlled feasibility study. Eur J Oncol Nurs. 2009;13:87-93. doi: 10.1016/j.ejon.2009.01.002
  4. Nakayama M, Okizaki A, Takahashi K. A randomized controlled trial for the effectiveness of aromatherapy in decreasing salivary gland damage following radioactive iodine therapy for differentiated thyroid cancer. BioMed Res Int. 2016;9509810. doi: 10.1155/2016/9509810
  5. Lua PL, Salihah N, Mazlan N. Effects of inhaled ginger aromatherapy on chemotherapy-induced nausea and vomiting and health-related quality of life in women with breast cancer. Complement Ther Med. 2015;23:396-404. doi: 10.1016/j.ctim.2015.03.009
  6. Rolim TL, Meireles DRP, Batista TM, et al. Toxicity and antitumor potential of Mesosphaerum sidifolium (Lamiaceae) oil and fenchone, its major component. BMC Complement Alt Med. 2017;17:347-59. doi: 10.1186/s12906-017-1779-z
  7. Saleh AM, Al-Qudah MA, Nasr A, et al. Comprehensive analysis of the chemical composition and in vitro cytotoxic mechanisms of Pallines spinosa flower and leaf essential oils against breast cancer cells. Cell Physiol Biochem. 2017;42:2043-65. doi: 10.1159/000479900
  8. Khan MA, Ali R, Parveen R, et al. Pharmacological evidences for cytotoxic and antitumor properties of Boswellic acids from Boswellia serrata. J Ethnopharmacol. 2016;191:315-23. doi: 10.1016/j.jep.2016.06.053
  9. Cho M, So I, Chun JN, Jeon JH. The antitumor effects of geraniol: modulation of cancer hallmark pathways. Int J Oncol. 2016;48:1772-82. doi: 10.3892/ijo.2016.3427
  10. Ambrož M, Matouškova P, Skarka A, et al. The effects of selected sesquiterpenes from Myrica rubra essential oil on the efficacy of doxorubicin in sensitive and resistant cancer cell lines. Molecules. 2017;22:1021-31. doi: 10.3390/molecules22061021

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Fact Sheet General Oncology