As someone already linked a great video, size doesn’t matter. You can apply any testing to breasts of any size.

Afaik, and I’ve looked into it several times over the years, size doesn’t influence tumor characteristics at all, in any way. You get variances in tumors, but that’s going to be more about how the cells behave as cells rather than the size of the breast.

As far as how the self exam is done, the main issue is being thorough, which can be difficult with unusually large breasts, but tends to be easy enough in any sizes you can pick up a bra for at some place like Wal-Mart. One of my exes had f cups, and self exams were no problem at all.

The process for a self exam is best described with pictures, or in video format Like this one, so I’m not going type it out when videos are easy to find :)

But it is exactly the same for even unusually large breasts, it just takes a little longer.

It’s also something I would recommend everyone learn how to do. As OP said, men can get cancer too, and self exams will detect it earlier. Plus, if you know how to do it, you can share that knowledge. I’ve taught women how to do a self exam because they were embarrassed to ask their doctor or nurses; they didn’t want to look “stupid” by not already knowing.

That’s a legitimate concern, btw. Women very often get treated different than men by providers, even when it’s a female provider. Showing up and not being able to fully advocate for one’s self makes that problem worse, and the idea of showing a lack of knowledge truthfully can end up with a provider treating you different. It can happen even when the provider knows that the discrepancy exists, and tries to minimize it. The subconscious is a powerful thing.

So, man or woman, learn how to do a self exam. Be willing to pass that knowledge on, with no jokes or comments. Be the kind of person that can be trusted to come to for that kind of thing. You might literally save a life, or at least some breasts.

Fwiw, that goes for testicular self exam too. A lot of guys don’t do them, and tend to dislike showing ignorance as well, so they end up in the same situation. So, man or woman, learn how.