Precision nutrition in breast cancer: Towards patient- and tumour-informed dietary strategies

Dietary strategies are increasingly recognized as important modulators of breast cancer outcomes, acting through effects on metabolic regulation, weight management, hormone signalling, immune function, and the gut microbiome. However, breast cancer heterogeneity and inter-individual variability mean that generic dietary guidelines may not fully capture patient needs. Precision nutrition offers the opportunity to align dietary interventions with tumour subtype, treatment context, and host biology, potentially enhancing therapeutic response and survivorship in patients diagnosed with breast cancer. In this narrative review, we summarize evidence on dietary patterns and prognosis, and explore how targeted interventions, including fasting regimens, ketogenic diets, and caloric restriction, may be informed by and targeted to host factors such as obesity, metabolic dysfunction, genetics and epigenetics, and microbiome composition, as well as tumour and treatment characteristics. We also discuss the emerging role of digital tools and multi-omics approaches to support personalization. While clinical translation is at an early stage, refining dietary recommendations through precision approaches may open new opportunities to improve prognosis and long-term care in breast cancer.