Would you offer reirradiation after resection of locally recurrent triple negative breast cancer only 6 months after completion of postmastectomy radiation?   

If recurrence is in the prior full dose of RT then get concerned about the efficacy of reradiation when it didn’t work 6 months ago. If it is marginal area or in an area where dosing was inadequate, then yes. Also if have hyperthermia then it would be a good modality to add with reradiation in...

I would agree with @Sushil Beriwal. If marginal and no other metastatic disease, I will use 40 Gy/10 fractions, twice weekly with hyperthermia.  If in field, we evaluate the role of systemic therapy, and if > 6 months from recurrence no other disease, I will consider the regimen above.