Link between thyroid hormone replacement, prostate cancer?

Hi everyone,

My long-term boyfriend has been taking synthetic thyroid hormone for the last year or two, prescribed by his doctor for low thyroid.

I thought I heard somewhere that there is a link between taking synthetic thyroid and prostate cancer. I know there's a link with breast cancer, but I haven't been able to find anything on the prostate.

Am I just remembering wrong, or does anyone here recall hearing something like that too, and maybe have some links?

Thanks!
RB:)