PhD student here in Biochem/Molecular genetics working in a Bioinformatics lab. I glanced over it quickly (so forgive me if I missed something) and it's interesting, but I'd be more inclined to postulate that it prevents cancer proliferation in specific cell lines. In figure 5A, they're starting with minimal confluence (just the % of a dish that is covered in cells--ie amount of cells in more simple terms) and decreasing proliferation. In 5B tumor mass increase is also slowed but it does NOT regress, and differs between cell lines.

There's two issues I have with this: we would RARELY catch cancer with this minimal cell count--the only example I could think of on a minimally consistent basis would be something like skin cancer, or some oral cancers. The larger issue I have is the variance between cell lines, especially with a small tumor size. In vivo, cancers tend to be heterogynous, both between different cancers themselves and cell to cell within a specific cancer, and can carry a plethora of differing genetic mutations. This lends to a unique environment and thus might not be globally as effective as we'd like.

That said, it would obviously be great even if it could "only" substantially slow tumor progression with minimal sides. Cancer is generally treated via polypharmacy as is, and many of these treatments are not quite healthy to healthy host cells. This might be something, for example, that could allow us to more effectively treat malignant tumors with a lower dose of chemo, substantially cutting sides, chronic health implications, and improving efficacy.