@Locksley I had similar pain in my right hand 2-3 months into my Letrozole. My GP sent me to do an MRI of the neck, which showed possible cause, but when I told my oncologist he said better to get checked for carpal tunnel instead. It wasn’t an invasive test, and was done publicly. The dr attached node-like things to my hand, then she used a machine to send pings (like an electrical current) to my hand and record the reaction on her computer. She did a series of similar tests with that little machine on both hands and it was relatively unpainful. It showed I was losing mass in my right hand and that yes, it was carpal tunnel. She advised to either change medication and get a shot, or to stay on the medication and have surgery. I chose to change medication and have the shots in both hands. It feels much better on the Arimidex and I’m having a reassessment test done next week so I can hopefully avoid surgery. Please ask your gp or onc to refer you to do a similar test as it’s best caught early.