I am going to have one of my testicles removed due to cancer. is this likely to reflect an alteration in any medication i take?

No, unlikely ...: There has been no known drug directly linked to testicular cancer. Generally speaking, a solid mass in testis has to be ruled out by surgical removal for microscopic evaluation after ultrasound study + blood tests as needed so to confirm what kink of cancer may be. So, ask and follow what the doctor will do for you. Best wish to your health...