Advanced-Technology Radiation Therapy for Bone Sarcomas

Samir Patel, MD; Thomas F. DeLaney, MD

Disclosures

Cancer Control. 2008;15(1):21-37. 

In This Article

Pelvic Sarcomas

Surgical resection has been used for the treatment of the primary tumor in the majority of patients with pelvic sarcomas, although for patients with radiation-sensitive tumors such as Ewing's sarcoma, primary RT has also been employed. Aggressive surgery improves local control in pelvic tumors.[80,81,82] Limb salvage is possible in patients with a pelvic sarcoma but such surgery is extensive and can be associated with a substantial rate of local complications along with functional and cosmetic disadvantages.[2,23,80,81,82,83]

Because radical surgery can cause severe morbidity, quality of life and function must be considered along with survival when outcomes are analyzed for these tumors.[84,85,86] Conventional RT for pelvic sarcomas can also be associated with significant morbidity. In young patients (median age 14.5 years) undergoing radiation in conjunction with chemotherapy for pelvic Ewing's sarcoma, significant late effects include muscular atrophy and limb length growth delay.[87] Recent planning studies have shown that protons deliver superior target dose coverage and better sparing of normal tissue than 3-D conformal radiotherapy or IMRT for pelvic sarcomas.[88] As dose-volume parameters are expected to correlate with acute and late toxicity, proton therapy should receive serious consideration as the preferred radiation technique for the treatment of these tumors. We have had some initial experience with management of these pelvic sarcomas. On the basis of our favorable experience with proton treatment for chondrosarcomas of the base of the skull with local control of 95% at 10 years[14] and our experience with protons for spine osteosarcomas and chondrosarcomas,[12] we have treated 3 patients who declined radical surgery for treatment of periacetabular chondrosarcomas. They were irradiated with protons following biopsy only or curettage and methylmethacrylate (MMA) cement or bone packing to doses of 74 CGE (Fig 8). With follow-up of 18 to 36 months, the tumor has been locally controlled in 2 of the patients; the third has experienced a marginal recurrence of tumor at the edge of the treated volume, requiring radical surgery for salvage. There has been no significant morbidity related to treatment to date and patients were able to ambulate free of assistive devices after radiotherapy. We have proposed a protocol of conservative surgery and proton RT as an alternative treatment for those patients with pelvic sarcomas who decline radical surgery. We think it is reasonable to also include patients with periacetabular and sacral osteosarcomas who decline radical surgery in the protocol based on recent data supporting a role for RT in patients with osteosarcomas who respond to chemotherapy.[6,89]

Axial display of the radiotherapy treatment plan for a 35-year-old patient with a low-grade chondrosarcoma of the left acetabulum, managed by local curettage, packing with autografted bone, and postoperative proton RT by shrinking field technique to a dose of 74 CGE in 37 fractions to the tumor bed. He is currently free of disease, walking with a normal gait without pain or need for assistive devices, and actively bicycling 3 years after completion of treatment.

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