Abstract: We identified 22 new trials for inclusion in this update. In total, the evidence of this review rests on 52 trials with a total of 3731 participants. We included music therapy interventions offered by trained music therapists, as well as music medicine interventions, which are defined as listening to pre-recorded music, offered by medical staff. We categorized 23 trials as music therapy trials and 29 as music medicine trials. The results suggest that music interventions may have a beneficial effect on anxiety in people with cancer, with a reported average anxiety reduction of 8.54 units (95% confidence interval (CI) −12.04 to −5.05, P < 0.0001) on the Spielberger State Anxiety Inventory - State Anxiety (STAI-S) scale (range 20 to 80) and −0.71 standardized units (13 studies, 1028 participants; 95% CI −0.98 to −0.43, P < 0.00001; low quality evidence) on other anxiety scales, a moderate to strong effect. Results also suggested a moderately strong, positive impact on depression (7 studies, 723 participants; standardized mean difference (SMD): −0.40, 95% CI −0.74 to −0.06, P = 0.02; very low quality evidence), but because of the very low quality of the evidence for this outcome, this result needs to be interpreted with caution. We found no support for an effect of music interventions on mood or distress. Music interventions may lead to small reductions in heart rate, respiratory rate and blood pressure but do not appear to impact oxygen saturation level. We found a large pain-reducing effect (7 studies, 528 participants; SMD: −0.91, 95% CI −1.46 to −0.36, P = 0.001, low quality evidence). In addition, music interventions had a small to moderate treatment effect on fatigue (6 studies, 253 participants; SMD: −0.38, 95% CI −0.72 to −0.04, P = 0.03; low quality evidence), but we did not find strong evidence for improvement in physical functioning. The results suggest a large effect of music interventions on patients' quality of life (QoL), but the results were highly inconsistent across studies, and the pooled effect size for the music medicine and music therapy studies was accompanied by a large confidence interval (SMD: 0.98, 95% CI −0.36 to 2.33, P = 0.15, low quality evidence). A comparison between music therapy and music medicine interventions suggests a moderate effect of music therapy interventions for patients' quality of life (QoL) (3 studies, 132 participants; SMD: 0.42, 95% CI 0.06 to 0.78, P = 0.02; very low quality evidence), but we found no evidence of an effect for music medicine interventions. A comparison between music therapy and music medicine studies was also possible for anxiety, depression and mood, but we found no difference between the two types of interventions for these outcomes. The results of single studies suggest that music listening may reduce the need for anesthetics and analgesics as well as decrease recovery time and duration of hospitalization, but more research is needed for these outcomes. We could not draw any conclusions regarding the effect of music interventions on immunologic functioning, coping, resilience or communication outcomes because either we could not pool the results of the studies that included these outcomes or we could only identify one trial. For spiritual well-being, we found no evidence of an effect in adolescents or young adults, and we could not draw any conclusions in adults. The majority of studies included in this review update presented a high risk of bias, and therefore the quality of evidence is low. This systematic review indicates that music interventions may have beneficial effects on anxiety, pain, fatigue and QoL in people with cancer. Furthermore, music may have a small effect on heart rate, respiratory rate and blood pressure. Most trials were at high risk of bias and, therefore, these results need to be interpreted with caution.

Plain-language summary: We identified 22 new studies, so the evidence in this review update now rests on 52 studies with 3731 participants. The findings suggest that music therapy and music medicine interventions may have a beneficial effect on anxiety, pain, fatigue, heart rate, respiratory rate and blood pressure in people with cancer. Because of the very low quality of the evidence for depression, it is unclear what impact music interventions may have. Music therapy but not music medicine interventions may improve patients' quality of life. We did not find evidence that music interventions improve mood, distress or physical functioning, but only a few trials studied these outcomes. We could not draw any conclusions about the effect of music interventions on immunologic functioning, coping, resilience or communication outcomes because there were not enough trials looking at these aspects. Therefore, more research is needed. No adverse effects of music interventions were reported. Most trials were at high risk of bias, so these results need to be interpreted with caution. We did not identify any conflicts of interests in the included studies. We conclude that music interventions may have beneficial effects on anxiety, pain, fatigue and quality of life (QoL) in people with cancer. Furthermore, music may have a small positive effect on heart rate, respiratory rate and blood pressure. Reduction of anxiety, fatigue and pain are important outcomes for people with cancer, as they have an impact on health and overall QoL. Therefore, we recommend considering the inclusion of music therapy and music medicine interventions in psychosocial cancer care.