How long after breast surgery is radiation?

It depends: Radiation may be given after a lumpectomy procedure. If chemotherapy is considered usually radiation will be given after completion of chemotherapy. In case of partial breast irradiation (brachytherapy), it is given shortly after lumpectomy whether or not chemotherapy is given. If radiation is needed after a mastectomy procedure, it is given after wound healing or after chemorx if chemorx needed.

Variable: To add a few points to dr. Vaziri's excellent answer...If no chemo is given post-op, radiation oncologists like to begin rx within 6 weeks. Another option available in some centers is intraoperative radiation therapy. As the name implies, rx is completed at the time of the lumpectomy. While not for everyone, this is a promising alternative that i believe will increase in usage in the future.