Chemotherapy-Induced Nausea and Vomiting

Chemotherapy-induced nausea and vomiting (CINV) develops in 70-80% of cancer patients undergoing chemotherapy. Nausea and vomiting are two of the most dreaded side effects that have pushed patients undergoing chemotherapy to consider delaying their treatments, or stopping chemotherapy entirely. Therefore, it is crucial to understand both drug and non-drug treatments to prevent and mitigate CINV, thereby improving patient compliance, outcomes, and quality of life.

Chemotherapy drugs are believed to produce nausea and vomiting by releasing serotonin in the small intestine that activates 5-HT3 receptors on vagal afferent nerves to trigger the vomiting reflex. While the 5-HT3 receptor has been demonstrated to selectively participate in the emetic response (i.e. vomiting), palonosetron (commonly known as Aloxi) is an effective 5-HT3 receptor antagonist that inhibits the release of serotonin. This prevents anticipatory nausea and vomiting (ANV), a type of CINV triggered by the smells, sights, and sounds of the treatment room.

Alternatively, drawing from the hypothesis that anxiety plays a role in exacerbating ANV, benzodiazepines like lorazepam have been commonly prescribed. In patients who experience nausea, the inhibitory action of gamma-aminobutyric acid (GABA), the neurotransmitter responsible for blocking neuronal excitability and therefore providing anxiety relief, is insufficient. Lorazepam functions by binding allosterically to benzodiazepine receptors in the post-synaptic GABA-A ligand-gated chloride ion channel in different sites of the central nervous system, as shown in the figure. This binding enhances the inhibitory effects of GABA, which increases the flow of chloride ions into the cell. The movement of chloride ions results in hyperpolarization which produces a calming effect and lowers anxiety levels.

However, as palonosetron is typically used in combination with other expensive antiemetic drugs, cost may be a barrier to prevention and mediation of CINV. For patients who cannot afford antiemetics due to a lack of insurance coverage, the need arises for a low-cost and accessible non-drug treatment.

Among non-drug treatments for CINV such as hypnosis, acupuncture, and guided imagery, music therapy has been shown to significantly improve nausea and vomiting in patients with gastrointestinal cancer during chemotherapy. Listening to music can reduce anxiety symptoms associated with nausea and vomiting. Music therapy can be applied to multiple patients at once while the same drugs cannot. Hence, music therapy is considered a non-drug treatment that is less costly and more accessible, giving it potential as an adjuvant treatment to antiemetic drugs.

The introduction of both drug and non-drug treatments opens opportunities for different combinations of complementary therapies to prevent and mediate CINV. As factors like younger age, female gender, and susceptibility to motion sickness may predict the risk of developing CINV, future study of other factors is required to better regulate CINV. A better understanding of biological, clinical, and genetic factors would enhance the ability to individualize treatment. The future of chemotherapy treatment lies in improving and developing different combinations of treatments to alleviate the side effects such as nausea and vomiting.