Shotgun metagenomic sequencing is currently the state-of-the-art method for analysing the taxonomic composition of the stools or ileal content using machine learning in cohorts of patients with cancer. Challenges in this field include designing user-friendly diagnosis devices and scores that need to be validated prospectively across different cancer types, staging, geographical regions, lifestyles, treatments and comorbidities. This score will be instrumental to stratify patients according to their degree of intestinal dysbiosis for future microbiota-centred interventions or interceptive measures. ICI, immune-checkpoint inhibitor; SGB, species-level genome bin.