Pulsed low-dose rate radiotherapy for recurrent bone sarcomas: case reports and brief review

Purpose: Re -irradiation for bulky recurrent sarcoma carries significant risks. Pulsed low -dose rate radiotherapy (PLDR) is an attractive option for re -irradiation due to inherent radiobiological advantages. Materials and Methods: We present two patients who underwent re -irradiation using PLDR technique, followed by a literature review. Results: The first case is that of a 76 -year -old male who developed an in -field recurrence of a bulky pelvic bone high-grade chondrosarcoma after he was treated with definitive radiotherapy using helical TomoTherapy with a total dose of 66 Gy. The patient was re -irradiated using PLDR with a shrinking field technique; 50 Gy in 2 Gy fractions followed by a boost of 20 Gy in 2 Gy fractions. The patient remains disease -free without significant toxicity 60 months post -irradiation. The second case is that of an 82 -year -old female who was treated with a definitive irradiation of 66 Gy in 33 fractions for a right shoulder grade II chondrosarcoma. She developed an in -field recurrence 28 months later and presented with bulky disease causing brachial plexopathy and lymphedema. The patient was re -irradiated with a palliative intent to a total dose of 50 Gy in 2 Gy fractions over 5 weeks using PLDR. Brachial plexopathy resolved shortly after re -irradiation, but local progression near the surface was evident 8 months later. She passed away from unrelated causes 11 months later. Conclusion: We present two cases highlighting our early experience with PLDR, which was effective in the re -irradiation of recurrent bony sarcoma. Our study highlights PLDR as an option for re -irradiation in recurrent unresectable tumors.