Effectiveness and Safety of Acupuncture for Cancer-Related Hiccups: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis investigated the efficacy and safety of acupuncture in the treatment of cancer-related hiccups, a symptom that affects 15-40% of oncology patients and can have a significant impact on quality of life. The researchers conducted a comprehensive search across eight databases, identifying nine randomized clinical trials that enrolled 580 patients. Cancer-related hiccups may result from central or peripheral organic lesions, oncologic treatments, electrolyte disturbances, or acid-base imbalances, causing not only involuntary diaphragmatic spasms but also insomnia, fatigue, malnutrition, depression, and irritability. The methodology followed the PRISMA 2020 guidelines and included frequency analysis of acupoint use.

The types of acupuncture studied were manual acupuncture, electroacupuncture, auricular acupuncture, and pressure needling. Control arms received pharmacologic treatments such as oral baclofen and metoclopramide injections. The meta-analysis results demonstrated that acupuncture was significantly superior to pharmacologic treatments in efficacy rate, with a relative risk of 1.83 (95% CI [1.53, 2.20], p < 0.001). Acupuncture also showed a faster onset of action, with a mean difference of -8.71 minutes compared with medications.

With respect to quality of life, acupuncture provided significant improvements in sleep, feeding, and appetite scores, with mean differences of 0.68, 0.68, and 0.66, respectively. Frequency analysis revealed that the points Zusanli (ST-36) and Neiguan (PC-6) were the most commonly used, present in seven of the nine studies. ST-36 belongs to the stomach meridian and PC-6 to the pericardium meridian, traditionally used to regulate stomach and spleen qi. Subgroup analysis showed that electroacupuncture was more effective than manual acupuncture, although with greater heterogeneity.

Regarding safety, acupuncture demonstrated a favorable profile, with only one patient reporting mild pain among 158 treated, and no serious adverse events were observed. Proposed mechanisms include improved blood flow to the hypothalamus, bidirectional regulation of gastrointestinal motility, influence on the neuroendocrine system through stimulation of nerve endings at acupuncture points, promoting production of neurotransmitters such as norepinephrine, serotonin, and gamma-aminobutyric acid. Acupuncture may also activate the cerebral cortex and suppress abnormal vagal nerve excitation. Despite the promising results, all important limitations must be considered.

All nine included studies had a high risk of bias, mainly due to lack of blinding of participants and clinicians, and problems with random sequence generation. Allocation concealment was inadequately reported in most studies, raising concerns about subjective selection. Significant heterogeneity persisted even after subgroup analyses and meta-regression, possibly due to differences in tumor types, intervention frequencies, and other design aspects. The small sample size and limited methodological quality of the included studies reduce the reliability of the results.

The clinical implications suggest that acupuncture may be a valuable alternative to pharmacologic treatments for cancer-related hiccups, especially given that conventional medications often cause adverse effects such as dizziness and excessive sedation in patients already debilitated by multiple therapies. Future research should focus on high-quality clinical trials, following the progression from exploratory to explanatory and confirmatory research, in addition to establishing unified diagnostic standards and clinical practice guidelines for cancer-related hiccups.