How Do Malignant Translocations Occur?

As you all should know synovial sarcoma is associated with a specific translocation between chromosomes 18 and X. NIH is trying to find out how such event occurred in the first place so they may find a way to prevent such event. Here are the findings so far:

http://www.nih.gov/news/health/sep2011/niams-29.htm?