No cancer, but there were reports years ago that the alum/aluminum in deodorants was linked to Alzheimers.
By the way ... SRD had the Shavex alum blocks for sale a few months ago, and the last time I ordered, it took several weeks as it was on backorder from Shavex ... maybe they discountinued due to the undependability of the supplier?
I like the interesting result from the Shavex alum block ... different than other astringents. I'm not sure the ultimate result is that much different though, than say, witch hazel ... but I do like it, so plan to keep it in the rotation.