If you look for information in "published" studies (eg do a search on medline) rather than any old website written by people that don't know that much about science, I think you will find that there is very little evidence that wearing a bra causes breast cancer. here are a selection of abstracts found on medline.

link1

a href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?itool=abstractplus&db=pubmed&cmd=Retrieve&dopt=abstractplus&list_uids=10360815">link2

link3