I may have been misinformed, actually. Looking into it further, it seems like mechanical interference in cell division was ruled out. However, it seems there is some evidence that among other things, fibers beyond a certain length cause macrophages to essentially get destroyed trying to engulf them, which contributes to chronic inflammation, which is a big risk factor in many cancers

It's a bit above my head but here is a study I found https://pmc.ncbi.nlm.nih.gov/articles/PMC7082251/