I'm Aliza, a BC patient and Medical Librarian. I'm extremely interested in your question and will definitely have to research it because I've been on Wellbutrin for about 15 years. I've been on Tamoxifen about a month. My oncologist never said a word to me and she certainly has my list of meds and I'm being treated at Memorial Sloan Kettering, so a bit later today I know what I'm doing. If I find anything, you'll be the second to know (after me...;)).
Thanks for bringing this interesting topic up to my attention. By the way, I had read re Tamoxifen on the package insert that weight loss was a side effect, so I was happy about that, if that give you comfort...;)