I don't know if you're familiar with the scientific publishing world, but there is a reason why this is published in a very cryptic journal with a dysmal impact factor of 0.7. We can discuss why this review is extremely weak in private if you wish :) And very importantly, and maybe you missed it, the abstract talks about combination of KD with other therapeutic approaches.

>Combining a ketogenic diet with standard chemotherapeutic and radiotherapeutic options may help improve tumor response, although more research is needed.

Combination approached have indeed shown promises in some models: for example a ketogenic diet greatly potentiates PI3K inhibitors in some models of cancer but is insufficient to reduce mortality by itself: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6197057/

This is undoubtedly an interesting research topic and it is very likely that diet can help in some (if not many) therapeutic settings. But claiming that it is enough to cure cancer by itself is just dangerous and wrong.