What's the optimal management of stage IA nodal ATLL in a young fit patient?

Patient in mid-30s with no major medical history presented with isolated left neck swelling. Incisional biopsy w/ HTLV1/2 associated ATLL, Ki67 of >90%. There was HTLV viremia (15,000 copies) but PET revealed only stage I disease, albeit with local invasion of subcutaneous tissues and skeletal muscle. Bone marrow biopsy and CSF sampling were negative. The patient was started on EPOCH, and achieved a PET complete response after 2 cycles. How best to consolidate? RT, alloSCT (DUBCT), or RT+allo?