I had my breasts radiated before starting ADT but it did not help much. However, radiation is used much more often than Tamoxifen.
Here is a trial about the use of Tamoxifen with Casodex and here is a review. Maybe you take that with you when you see your URO.
In 2013, my RO wasn't a fan of breast irradiation, nor Tamoxifen. He didn't think the potential benefits outweighed the risks of either approach. His suggestion was that if gynecomastia did develop (it doesn't for everyone), and if it was bothersome, that surgery after the fact was the safest option. Of course that has other issues, not least because it's elective surgery and not covered by insurance.
Our forum boffin Tall Allen almost always suggests Tamoxifen, and I'm sure has links showing why it is a decent option.
Of all the ADT side effects, that was the least of my concerns. There's a bunch of oh-so-wonderful side effects that have significantly more impact on quality of life than the mere vanity impact of somewhat enlarged breasts. Fatigue was the worst by far.