Plastics have become integral to modern life, but their persistence has generated vast quantities of microplastics (MPs, <5 mm) and nanoplastics (NPs, <1 µm) that now contaminate food, water, air, and human tissues. Although not yet classified as carcinogens by the International Agency for Research on Cancer, accumulating experimental and epidemiologic evidence raises concern that MPs may contribute to cancer development. Global plastic production has risen from 2 megatons in 1950 to more than 450 megatons annually in 2022, leaving behind pervasive waste that fragments into MPs and NPs. These particles act as xenobiotics, carrying toxic additives and adsorbed pollutants, provoking oxidative stress, chronic inflammation, DNA damage, and microbiome disruption; all processes central to carcinogenesis. MPs have been detected in human cancers, and animal studies show tissue accumulation, fibrosis, and genomic instability following exposure. Importantly, the proliferation of plastics parallels a global rise in early-onset cancers (diagnosed before age 50), suggesting a possible, though unproven, temporal association. Individuals born after the 1950s plastic boom have experienced continuous MP exposure beginning in utero, potentially predisposing them to carcinogenic pathways later in life. In this review, we integrate human biomonitoring data, experimental findings, and clinical observations to evaluate the emerging hypothesis that chronic MP exposure contributes to cancer risk. While causality has not been established, the biological plausibility and mounting evidence underscore the urgent need for mechanistic and epidemiologic studies to clarify the role of MPs and NPs in cancer development. It also underscores an urgent need for research into causal pathways and preventive mechanisms.

Rhabdomyosarcoma (RMS) is a predominantly paediatric cancer that is classified by the presence or absence of a PAX-FOXO1 fusion gene, which is associated with a worse prognosis. Previous classification was based on histology, alveolar RMS (ARMS) or embryonal RMS (ERMS). In other paediatric cancers, fusion gene status has been shown to associate with differences in the tumour microenvironment (TME). However, comprehensive understanding of the TME in RMS and how it may differ between subtypes is lacking. This systematic review aimed to identify differences in the TME between fusion-positive RMS and fusion-negative RMS, to better understand how the fusion gene drives malignancy. The Web of Science, MEDLINE (Ovid), and EMBASE (Ovid) were searched to identify relevant studies investigating the TME in RMS. A total of 17 studies met the inclusion criteria and were included in the review, but only three studies specified fusion status in their sample data. Nine studies investigated the extracellular matrix and stroma, and another nine investigated the immune microenvironment. Significant differences in CD163+ macrophages, matrix metalloproteinases and stromal platelet-derived growth factor receptors-α/β were observed between ARMS and ERMS. Regarding fusion status, there were differences in the prevalence of T cell dysfunction, NECTIN-3 expression, and genes related to PD-1 signalling and interferon (IFN) response. This review highlights a need for further research of the TME in each fusion subtype. This will improve our understanding of how the fusion gene drives malignancy and ultimately aids in the development of novel treatment strategies.