I'd reiterate the advice given in your other question - do not use the sap on your skin, it is highly irritant and in some people will cause a serious allergic reaction.

If you have good reason to be anxious about skin cancer you should see a doctor. If you are concerned about skin cancer but have no signs of it just be sensible don't overdo the sunbathing especially in the middle of the day, & wear a good sun screen. Euphorbia sap can irritate even skin on your hands and arms, never mind your face.

I expect Coppertops is trying to avoid the need for having more growths removed at a later date...

How daft can you get - I read the 4 cut out as 4 euphorbias cut and ready for planting! You wouldn't believe it would you....
But all the same the advice not to use the euphorbia still stands.