Efficacy of Auricular Acupressure in Prevention and Treatment of Chemotherapy-Induced Nausea and Vomiting in Patients with Cancer: A Systematic Review and Meta-Analysis

Nausea and vomiting are among the most debilitating side effects faced by cancer patients during chemotherapy, affecting more than 40% of patients even with the use of modern antiemetic medications. These symptoms not only significantly impair patients' quality of life, but can also interfere with treatment adherence, leading some patients to delay or discontinue chemotherapy. Delayed vomiting, which occurs 2 to 5 days after chemotherapy, is particularly challenging to treat due to the rapid onset and short half-life of conventional antiemetic medications. In addition, many of these medications cause side effects such as constipation, fatigue, dizziness, and diarrhea, limiting their repeated use.

In the face of these challenges, auricular acupressure emerges as a promising and noninvasive alternative based on Traditional Chinese Medicine. This technique uses small seeds or magnetic spheres applied to specific points in the ear, providing continuous stimulation without causing pain or discomfort. The researchers conducted a systematic review and meta-analysis to scientifically evaluate the efficacy of auricular acupressure in the prevention and treatment of chemotherapy-induced nausea and vomiting. The study followed rigorous methodology, searching eight international and Chinese scientific databases from their inception through April 2020.

The inclusion criteria covered only randomized controlled trials that compared auricular acupressure alone or combined with antiemetic medications versus standard treatment or placebo in cancer patients undergoing chemotherapy.

The analysis included 19 randomized controlled trials involving 1,449 patients with various types of cancer, published between 2011 and 2020. The studies used 19 different auricular points, the most frequent being: Stomach (used in 100% of the studies), Shenmen (94.7%), Sympathetic (73.7%), Spleen (63.2%), Subcortex (52.6%), and Liver (31.6%). Most studies compared auricular acupressure combined with antiemetic medications versus antiemetics alone. The researchers separately evaluated efficacy for nausea and vomiting, also taking into account the timing of symptoms (acute — first 24 hours, and delayed — days 2 to 5 after chemotherapy).

The results demonstrated significant benefits of auricular acupressure, particularly when combined with antiemetic medications. Overall efficiency in relieving nausea and vomiting was 31% greater in the group that received auricular acupressure combined with antiemetics compared with the control group. For delayed symptoms specifically, the results were even more promising: the frequency of delayed nausea was reduced by 32% and the frequency of delayed vomiting by 68%. Interestingly, the technique was less effective for acute symptoms, suggesting that its action is more sustained and complementary to fast-acting medications.

In addition to the direct benefits on nausea and vomiting, auricular acupressure significantly reduced side effects of antiemetic medications, including constipation (39% reduction), diarrhea (34% reduction), and fatigue (61% reduction).

For patients and their families, these results offer hope of better control over the most feared symptoms of chemotherapy. Auricular acupressure represents a safe, noninvasive, and low-cost option that can easily be integrated into conventional treatment. Health care professionals can consider this technique as a complementary therapy, especially for patients who experience persistent or delayed nausea and vomiting, or those who suffer significant side effects from antiemetic medications. The technique involves the placement of small seeds or spheres at specific points on the ear, which remain in place for several days, providing continuous stimulation.

The mechanism of action is based on the stimulation of neural pathways that modulate the brain centers responsible for nausea and vomiting.

Despite the encouraging results, the study has important limitations that should be considered. The clinical heterogeneity among the included studies, with different cancer types, chemotherapy regimens, and acupressure protocols, reduces confidence in the results. There is no standardization in the selection of auricular points, duration of pressure, frequency of seed replacement, or qualification of the providers, which makes it difficult to reproduce the results in clinical practice. Most studies had small samples, and only one study included children, limiting the generalizability of the findings.

In addition, due to the characteristics of the intervention, it was difficult to implement adequate blinding in the studies, which may have influenced the results.

In conclusion, this meta-analysis provides robust scientific evidence that auricular acupressure, especially when combined with antiemetic medications, offers significant benefits in controlling chemotherapy-induced delayed nausea and vomiting, in addition to reducing side effects of conventional medications. The authors recommend the technique as a complementary therapy in the management of these symptoms, particularly for patients with persistent symptoms. However, future studies with larger samples, standardized protocols, and more rigorous methodological designs are needed to definitively confirm the efficacy of auricular acupressure alone and to establish clear guidelines for its clinical implementation.