Is it true when you block your sweat glands using clinical strengths antiperspirants you're at risk of developing cancer?

There's not a lot of data to support this report as true. It simply needs to be studied more. However, underarm sweat can be better treated permanently with MiraDry.
See my video link below. 
Good luck. Dr. ALDO 

There is no direct study that confirms this association, however a study did find higher incidence in breast cancer in young females than older ones and one theory was the earlier use of antiperspirants.  Due to this study, the popularity in natural deodorants has risen as a "safer" approach.

Great question. There are several studies that are looking into the possibility of a link between cancer and the aluminum in antiperspirants, but there is nothing (to my knowledge) that confirms the link at this point. However, I do have a great article on how Botox for Hyperhidrosis can be safer than antiperspirants. Take a look!

Thank you for sharing your question.  In the majority of deodorants the anti-perspirant quality is derived from the use of aluminum.  Whether prescription strength or not, it does not increase your risk of developing cancer.  Hope this helps.

It is safe in the sense that it won't cause you to overheat.
The long term consequences for the use of alum chloride containing compounds on the development of breast cancer is not convincingly known. I do not believe it causes hydradenitis.
H Karamanoukian MD FACS
CEnter for Excessive Sweating, established 1999