>However, it is what the article implies.

No, it doesn't: while it is true that cancer death is due to metastasis in 90% of cases, this approach wouldn't affect pre-existing metastasis at all (it only affects the motility of cancer cells, so the propensity of a cancer to metastasize). So if you have metastasis at the time of diagnosis, which is the case in most deadly cancer, this approach is most likely completely useless. And if you don't have metastasis at the time of diagnosis, this approach is also in most cases irrelevant, because the way to go is simply surgical removal of the primary tumor. Diagnosis without mets is generally refered to as stage 1 cancer and often has very low mortality, with some exceptions.