Microplastics (MPs), we are learning, are everywhere and implicated in a growing number of cancers. Now, a Chinese team has new evidence that they cause colorectal cancer (CRC). This study identified MPs in both peritumoral and tumor tissues of colorectal cancer patients, highlighting their accumulation in human cancers. Previous research has shown MP accumulation in other human organs, such as the lungs and liver.
The presence of MPs in both peritumoral and tumor tissues, the authors say, “raises questions regarding the role of environmental pollutants in cancer development.”
The study appears in Scientific Reports and the lead author is Wen Pan of China’s National Clinical Research Center for Cancer.
Recently, there has been lots of attention to the widespread occurrence of MPs in the environment and this has raised a lot of concerns regarding their potential health impacts, particularly in relation to carcinogenesis.
Microplastics are plastic particles less than five millimeters in diameter that can trigger cytotoxicity and chronic inflammation, and may promote cancer through processes such as pro-inflammatory responses, oxidative stress, and endocrine disruption.
CRC, meanwhile, is the third most common type of cancer diagnosed, and it has been increasing in frequency among young people.
This Chinese study aimed to identify and analyze microplastics present in peritumoral and tumor tissues of patients diagnosed with CRC. Using advanced scanning electron microscopy and laser direct infrared imaging systems, the team examined tissue samples to detect and characterize the microplastics.
They found a diverse array of microplastic types, notably polyvinyl chloride (PVC) and polyethylene (PE), within both peritumoral and tumor regions. Compared to adjacent non-cancerous tissues, tumor tissues exhibited a greater variety and distribution of microplastics. Furthermore, Clathrin—a key protein involved in endocytosis—was found to be highly expressed in colorectal cancer specimens, facilitating the substantial uptake of microplastics.
The researchers found a different concentration of MPs in tumor tissues compared to adjacent peritumoral tissues, consistent with previous research showing MP accumulation in human organs, such as the lungs and liver.
Characterization showed that most MPs were smaller than 100 μm and consisted of PE, PVC, and PET. Their small size, the researchers wrote, allows penetration into cells, potentially disrupting their function, signaling, or inducing genotoxic effects. MPs with rough surfaces may increase cell interactions, triggering chronic inflammation linked to colorectal cancer, promoting mutations, and fostering tumor growth.
The authors wrote, ”This suggests that MPs may contribute to or be retained in the tumor environment, potentially triggering inflammation, oxidative stress, and immune dysregulation, all of which are linked to cancer progression.”
These results point to a potential association between exposure to MPs and risk of colorectal cancer. The authors say it “ highlights the urgent need for increased awareness and regulatory measures aimed at mitigating microplastic pollution along with its associated health risks.”
