The clinical relevance of microplastic exposure on colorectal cancer: A systematic review

Microplastic exposure can contaminate multiple organs through nasal, dermal, and respiratory routes. The effect of microplastic exposure on colorectal adenocarcinoma development has gained attention. This systematic review aimed to summarize studies of microplastic exposure in humans with colorectal cancer. The relevant studies were collected through a computer-assisted search in PubMed, ISI Web of Science, Embase, Scopus, and Google Scholar databases. A total of 747 documents were evaluated for eligibility by two independent authors. The quality assessment of eligible studies was evaluated by the JBI checklist, and required data were collected and extracted from the included studies. After analysis, four studies were found eligible. The microplastic infiltration in colorectal tissue biopsies was relatively high; polyamide, polycarbonate, and polypropylene polymers were among the most common polymers in colorectal tissue samples of patients with colorectal adenocarcinoma. The average particle size was 0.1 µm to 1.6 mm. Microplastics shape in colorectal cancerous tissue, including fibers, fragments, and films. Microplastic abundance in colorectal tumor tissue was 25.9-32.2 particles/g tissue. In the case-control study, the microplastic accumulation in colorectal cancer tissue samples was significantly higher than in controls. The etiology of colorectal cancer remains unclear; however, environmental factors are actively contributing to colorectal cancer development. While there are few studies on microplastics in patients with colorectal adenocarcinoma, existing evidence indicates microplastic accumulation in the colorectal tissue of these patients. Further research is needed to determine if microplastic exposure initiates or leads to the development of colorectal cancer events.