Nick Robinson is confused

Nick Robinson reports on his BBC blog that

"I began a spot of moonlighting presenting the Today programme on Radio 4 this morning. Feeling pretty smug at not messing up I emerged from the studio to be told that I'd spent the whole of a discussion about a possible cure for cancer referring to prostrate instead of prostate cancer."

I presume that Nick Robinson is thinking of how he normally prostrates himself in front of the Labour politician he is interviewing.