Peyronie's, Dupuytren's, and Ledderhose are all related diseases; plaque and pain and resulting deformation of the penis, hands, and feet, respectively, right?
Does one cause another? Or is it just that your underlying genetics or pathology makes you at higher risk?
My uro said yes that having Peyronie's, I am definitely at a higher risk for the other. But does/can one cause another directly? I would assume any risk is at a genetic level...not necessarily plaque (i.e., if you have plaque in your penis, the presence of it there would not directly cause plaque in the hand), and vice versa...but your underlying conditions that caused it in the first place may also make you at elevated risk.)
What about cancers? Penile or testicular cancer? Something else?
Put more simply - what else do I need to worry about now that I have Peyronies Disease?
How common is it that someone with one gets another?
You had it right - it is just the underlying genetics that puts you at higher risk.
I wouldn't worry about it too much though - if it is going to happen, there is nothing you can do to prevent it. And of course there is the chance that you only develop Peyronie's Disease and not the others.
There is no connection between Peyronie's Disease and cancer.