Term for puns in graphics - "Can"cer be beaten

I think you are looking for something like "rebus". It was a type of visual pun. It used to strictly be with icons but it can be done through text.

https://en.wikipedia.org/wiki/Rebus

I've found the term typographic pun. It is mentioned as a kind of connotative typograhic treatment in the book Street-Smart Advertising: How to Win the Battle of the Buzz (by Margo Berman). The book says that when connotative type works as part of the concept (main message), it contributes to the overall idea of the promotional material. It is the combining of the verbal and visual message into one total expression.

Here is the relevant excerpt from the book:

This might be known as a double entendre, where a phrase is open to two interpretations. The secondary meaning is often of indecent or sexualized meaning, but it does not always have to be.