Post operative radio therapy indication for sarcomas depends on many factors like , margin status , closest margin , grade of tumor , and potential for a surgical treatment of recurrence occur etc.
In your case the treating doctor may have found enough indication for giving radiotherapy , that may be the reason for him to suggest the treatment.
Yes , even after complete removal of breast , there is high chance of recurrence in some cases . In such cases , we do recommend radio therapy to the local site , to reduce that recurrence probability . And the timing of this radiotherapy is as soon as possible after healing of surgical wound usually started within 6 weeks .
Next Steps
Hope the answer is clear , can give you a better opinion based on indications in your cases if you can review with initial MRI , post of HPR reports
Health Tips
Continue treatment as advised , delay may have adverse effect on prognosis