I think the high end of recurrance with lumpectomy and rads is about 15%.
Generally, young women tend to have higher risk of recurrence. In young women with a family history of breast cancer, the risk of a new primary can be as high as 40% (BRCA or no BRCA).
http://www.medicalnewstoday.com/articles/4608.php
http://www.emaxhealth.com/98/4983.html
http://jco.ascopubs.org/cgi/content/full/19/18/3798
As with all things, an individual's risk may be very different from the group risk. (If you're the one in a million, then it's 100% for you.)
Tammy Lou