Wow. That's a grosely misinformed "specialist". Kinda embarrassed for him. The risk is actually unfounded. There's absolutely no firm evidence that not having a hysterectomy leads to cancer. The research just isn't there. It really is just an assumption right now. But without a proper study, it's kinda bad for anyone to point blank state figures, especially this 10% thing. Where'd he pull that number from? It's simple enough to do a search online. the studies just aren't there, so he's, quite frankly, talking out of his ass! He's just assuming everything he's stated and then admitted that there aren't enough studies. What is it? 10% or we need more studies? It can't be both! Sometimes I really do worry about some medical "professionals".
You don't need to have one but it is advised, it's all just junk when you're on T anyway. While there's no studies proving increased risk, there is still the possibility of an increased risk and it doesn't take away the risk you already have just by having them, so it is generally safer to just be without really.
Depending on where you live it can also make the difference when it comes to being male or female on documents like birth certificates or medical records. Also, after a hysterectomy (assuming you specify the cervix is removed) you no longer have to go through any gyn screening examinations.