Salivary microbiome and metabolome profiles in rectal cancer patients with and without prior pelvic radiotherapy

The study comprised patients with rectal cancer who had received pelvic radiotherapy (RG), patients with rectal cancer who had not received radiotherapy before sampling (NRG), and hospital-based non-cancer controls (HG). All archived samples available during the study period were screened against the prespecified eligibility and laboratory quality criteria.

The sample size was determined by the number of eligible archived samples available rather than by a prospective power calculation. Of the samples screened, 38 met all eligibility and quality-control requirements and were included in the analysis.Participants were eligible if they were 18–80 years of age, irrespective of sex. Patients in the RG and NRG groups had histologically confirmed rectal adenocarcinoma, with the lower tumour margin located 3–12 cm from the anal verge on colonoscopy.