Impact of probiotic supplementation on chemotherapy and radiotherapy-associated diarrhea and quality of life

OBJECTIVES: To evaluate whether prophylactic oral Lactobacillus supplementation reduces chemotherapy- and radiotherapy-associated diarrhea and helps preserve quality of life (QoL) in adults starting anticancer treatment. MATERIALS AND METHODS: This prospective two-group observational study included adults (18–75 years) receiving their first cycle of chemotherapy and/or radiotherapy at a tertiary cancer center. The Nonprobiotic Group received standard care without probiotics, and the Probiotic Group received standard care plus oral Lactobacillus 60 million colony-forming units twice daily for 6 weeks. Diarrhea was graded using the National Cancer Institute Common Terminology Criteria for Adverse Events version 5.0. Use of rescue loperamide, pain on a 10-cm Visual Analog Scale (VAS), and scores on the European Organisation for Research and Treatment of Cancer QoL Questionnaire Core 30 (EORTC QLQ-C30) were recorded at baseline and at 6 weeks. RESULTS: One hundred patients completed follow-up (50 per group). At 6 weeks, Grade ≥ 2 diarrhea occurred in 28% of the Nonprobiotic and 4% of the Probiotic Group. Mean diarrhea score was higher without probiotics (1.26 ± 0.49 vs. 0.78 ± 0.51, P < 0.001), and loperamide use was more frequent (44% vs. 24%, P = 0.034). VAS pain scores decreased significantly over time in both groups. Physical functioning at 6 weeks was slightly better in the probiotic group, while other EORTC QLQ-C30 domains were broadly comparable. CONCLUSION: Prophylactic Lactobacillus supplementation was associated with milder treatment-related diarrhoea, reduced rescue loperamide use, and small early gains in physical functioning during chemoradiotherapy.