Acupuncture for the prevention of chemotherapy-induced nausea and vomiting in cancer patients: A systematic review and meta-analysis

Chemotherapy-induced nausea and vomiting are among the most distressing adverse effects faced by patients with cancer. When not treated adequately, these symptoms can affect between 60% and 80% of patients, causing significant suffering, compromising quality of life, and potentially leading to abandonment of oncologic treatment. Although modern antiemetic medications have dramatically improved prevention of these symptoms, approximately one-third of patients still experience nausea and vomiting even with medications. In addition, the financial costs of these medications can be substantial.

Given these limitations, the search for complementary approaches such as acupuncture has gained growing interest in the medical community.

This study represents the most comprehensive systematic review to date on the efficacy of acupuncture in the prevention of chemotherapy-induced nausea and vomiting. The researchers conducted an extensive search of eight electronic databases, including Chinese and international sources, identifying randomized controlled clinical trials that compared acupuncture with real needles versus sham acupuncture or usual care. The main objective was to evaluate whether acupuncture could increase complete control of these symptoms, defined as the absence of vomiting episodes and the presence of only mild or no nausea. The researchers also specifically investigated factors that could influence treatment effectiveness, analyzing different characteristics of the studies and patients.

The analysis included 38 clinical trials involving 2,503 patients with cancer. Most studies were conducted in China, with patients presenting various types of cancer, mainly lung and breast. The most frequently used acupuncture points were Zusanli, Neiguan, and Zhongwan, known for their gastrointestinal discomfort relief properties. The results showed that when acupuncture was added to usual care, there was an increase in the chance of complete control of acute vomiting, which occurs in the first 24 hours after chemotherapy, and of delayed vomiting, which occurs between 24 and 120 hours after treatment.

Specifically, a 13% increase in the chance of controlling acute vomiting and a 47% increase for delayed vomiting were observed. However, no significant benefits were found for nausea control, whether in the acute or delayed phase.

For patients and health professionals, these results suggest that acupuncture may be a useful complementary option, especially for the control of chemotherapy-related vomiting. It is important to note that acupuncture proved to be relatively safe, with adverse events generally being mild, such as pain at the needle insertion site or small hematomas. The fact that acupuncture showed greater efficacy for vomiting than for nausea may be explained by physiological differences between these symptoms: vomiting is a more objective and measurable event, while nausea is a more subjective sensation that is more difficult to assess and control. For professionals considering incorporating acupuncture into oncology care protocols, the findings indicate that it may be particularly beneficial when used as adjuvant treatment to conventional antiemetic medications.

However, it is essential to recognize the important limitations of this study. The quality of the evidence was classified as very low to low, mainly due to methodological problems in the analyzed studies. Most studies were unable to adequately mask patients regarding which treatment they were receiving, which may have influenced the results. In addition, there was great variability in acupuncture application methods, points used, treatment duration, and ways of measuring results, making it difficult to compare studies with each other.

Another concerning aspect was the suspicion of publication bias, suggesting that studies with negative results may not have been published. When acupuncture was directly compared with sham acupuncture (where needles are inserted at non-therapeutic points), no significant benefits were found, raising questions about whether the observed effects are specific to acupuncture or related to other treatment factors.

The researchers conclude that, although acupuncture may offer some additional benefit when combined with standard care to control chemotherapy-related vomiting, current evidence is uncertain and of limited quality. To definitively establish the role of acupuncture in this context, future studies with better methodological quality, larger patient samples, more standardized treatment protocols, and uniform outcome measures are needed. Until more robust evidence is available, patients and clinicians should carefully discuss the potential benefits and limitations of acupuncture as part of an integrated approach to the management of chemotherapy-induced nausea and vomiting, always maintaining conventional treatments as the basis of care.