Abstract
The effects of a plant-based immunomodulator, rice bran arabinoxylan compound (RBAC), on the quality of life (QoL) of cancer patients during active treatment are unclear. The RBAC-QoL study was a randomised, placebo-controlled, double-blind feasibility study to address the role of RBAC in cancer patients receiving systemic therapies. The primary outcome measure was patient-reported functional, symptom, and global QoL scores. Secondary and exploratory outcome measures included nutritional indices and cytokine changes. Adult patients (n = 29) with solid organ tumours (≥ stage II) undergoing systemic treatment were recruited from outpatient centres in New South Wales, Australia. Group allocation was assigned through stratified randomisation (RBAC = 12, placebo = 17). Interventions were either RBAC or matched placebo at 3 g/day for 24 weeks. The participants, oncologists, and data collectors were blinded. Data were collected from five study visits, 6 weeks apart. An intention-to-treat analysis was performed using repeated measure ANOVA with pairwise comparisons where statistical significance was observed. Data sets not conforming to normality were tested with nonparametric ANOVA-type statistics. The global QoL scores differed significantly between groups with a large effect size (p = 0.031, eta(2)[g] = 0.147). Pairwise comparisons found significant differences favouring the RBAC group at week 6 (p = 0.017, Cohen’s d = 1.119) and week 24 (p = 0.041, d = 0.970). Compared to the placebo group, the RBAC group showed significantly better role (p < 0.001) and social functioning (p = 0.037), while the cognitive functioning score difference was trending higher (p = 0.055). Regarding cancer symptoms, the placebo group reported significantly worse scores (p < 0.05) in fatigue, pain, dyspnoea, and appetite loss compared to the RBAC group. Significant elevations (p < 0.05) of cytokine interferon-γ, interleukin 1RA and 12p40, as well as total protein, were also detected in the RBAC group compared to placebo over time. These serum markers correlated positively with the global QoL scores, suggesting potential interactions of immune activity, nutritional status, and QoL. No intervention-related adverse events were reported in both groups. RBAC improves QoL beyond placebo during systemic cancer treatment, potentially through the immuno-nutritional pathway. Trial registration: Prospective registration on the Australian New Zealand Clinical Trials Registry (ANZCTR Reg No: ACTRN12619000562178p, 10/04/2019). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1038/s41598-026-41554-8.