Harms of massage in persons with cancer or receiving treatment for cancer: A systematic review and meta-analysis

Introduction: Massage is widely used in cancer survivors. However, formal assessment of potential harms is lacking. The aim of this study is to assess harms related to massage. Materials and methods: This systematic review and meta-analysis included studies that compared massage with control conditions, in people with- and/or receiving treatment for cancer. The primary outcome was adverse events. Ten databases and trials registries were searched up to 22 October 2024. Quality of adverse events reporting was assessed as adherence to the CONSORT statement extension for reporting of harms. Studies reporting on adverse events were assessed for risk of bias using the PEDro scale (randomized controlled/ cross-over trials) and ROBINS-I (quasi-experimental and cohort) and were eligible for meta-analysis (random-effect). The study was registered at PROSPERO (CRD42023352993). Results: Sixty-three intervention studies were included, of which 53% (n = 34 studies) did not report on adverse events. Twenty-nine studies (n = 2699) reported on adverse events explicity and/or as study discontinuation. Of these, no studies assessed deep massage, with most interventions using light massage. Meta-analyses indicated no evidence of a higher risk of adverse events related to massage compared to usual care/attention control. Three cohort studies (n = 1406) were included, two of which (both with critical risk of bias) found significant associations between massage over tumor site and negative survival outcomes, in patients with osteosarcoma. Overall, the quality of adverse events reporting was poor, and certainty of evidence considered very low. Conclusion: Results indicate that light to moderate intensity massage in people living with- and/or receiving treatment for cancer can be performed without increased risk of harms. Contraindications for massage should be applied as per the general population. Due to uncertainty as to whether massage over tumor in osteosarcoma constitutes an increased risk of negative survival outcomes, massage directly on tumor is discouraged, though definitive evidence is lacking.