Microplastics and prostate cancer.

379 Background: Plastics are ubiquitous in our environment. Tiny plastic particles called microplastics and nanoplastics (MNPs) have been found in many human tissues. A recent study of patients undergoing carotid endarterectomy found that patients with MNPs in their plaques were 4.5 times more likely to experience myocardial infarction, stroke or death. Preclinical data also suggests a potential link of MNPs with cancer; however, direct evidence of a link to human prostate cancer (PCa) is limited. The objective of our study was to determine whether MNPs are found in human PCa, and to compare levels of MNPs between tumor tissue versus benign tissue. Methods: We recruited 10 patients with PCa undergoing radical prostatectomy. The prostatectomy specimen was transported in a metal container, and underwent plastic-free pathological evaluation by an expert uro-pathologist. Separate samples of tumor tissue and benign tissue from elsewhere in the prostate were then transferred to the lab where we used 2 different techniques for MNP evaluation: (1) visual inspection in tandem with Raman microscopy to assess MNP particle abundance, size, and other characteristics, and (2) pyrolysis-Gas Chromatography/Mass Spectrometry (py-GC/MS) to identify and quantify MNPs on a mass basis. Descriptive statistics were used to tally the type and concentration of MNPs identified. Results: Microplastic particles were detected in 60% of patient samples using Raman, with individual particles ranging from 1.2 µm to 40.3 µm in diameter. Tumor tissue had a greater number of particles per sample than benign tissue. Using Py-GC/MS, we found MNPs in 90% of patients (90% of tumor and 70% of adjacent benign tissue). Tumor tissue concentrations of microplastics tended to be higher than para-tumor tissue concentrations. The mean concentration of MNP was 39.8 (µg/g) (median 16.3) in tumor tissue, compared to a mean of 15.5 (µg/g) (median 7.0) in adjacent benign tissue. With respect to particle types, nylon-6 and polystyrene were found above the method detection limit in the largest number of samples using py-GC/MS, while polyethylene and polyethylene copolymers were also identified on Raman. Conclusions: Microplastics were found in tissue samples from 9 out of 10 patients with prostate cancer using either method, with greater concentration in tumor tissue compared to benign tissue. Additional research is in progress to study the link between MNPs with prostate carcinogenesis. Supported by the Department of Defense HT9425-25-1-0145.