colorectal cancer and lactobacillus plantarum: a qpcr-based study of ffpe tissues

Introduction: colorectal cancer (crc) is a major global health issue. the gut microbiota has become an important factor in crc development, with increased focus on microbes such as lactobacillus plantarum. this study aimed to examine the presence and relative abundance (gapdh-normalised copy number) of l. plantarum in colorectal tissues using a qpcr approach.materials & methods: dna was extracted from formalin-fixed paraffin-embedded (ffpe) tissues from three groups: tumour tissues from crc patients (n = 50), matched adjacent normal tissues (n = 50), and normal tissues from individuals without crc (n = 30). species-specific primers targeting the groel gene were used to measure l. plantarum, normalised against human gapdh. statistical analyses compared occurrence and levels across groups and assessed associations with age and sex.results:  although bacterial load did not vary significantly across tumour, adjacent, and normal tissues, detection frequency was higher in tumour tissues (p = 0.0459). l. plantarum was also detected more often in individuals aged ≥60 (p = 0.0024). subgroup analysis revealed higher loads in normal tissues of older adults and females and lower abundance in adjacent tissues of females.conclusion:  l. plantarum was detected more frequently in tumour tissues despite consistent bacterial loads, indicating possible persistence rather than growth. these findings highlight age-, sex-, and tissue-specific colonisation patterns and emphasise the need for further research on the tumour-associated ecology of beneficial microbes.