NEW YORK (Reuters Health) Apr 29 - Proton-based radiotherapy provides local control for 5 years in nearly three-quarters of patients with unresectable or incompletely resected osteosarcoma, according to a report in the March 29th online Cancer.
"Osteosarcomas arising in the axial spine, pelvis, or skull have traditionally been very difficult to treat," Dr. Thomas F. DeLaney from Massachusetts General Hospital, Boston, told Reuters Health in an email. "They require high radiation doses for local tumor control. Protons, with no exit radiation dose beyond the tumor, allow high-dose radiation, in combination with chemotherapy, while sufficiently sparing normal tissue to control some of the challenging osteosarcomas."
The cost of proton-based radiotherapy, Dr. DeLaney said, "is higher in the short term, but may be less expensive than IMRT photons in the long run because of fewer treatment-associated late effects, i.e., cardiac, second tumors, etc."
Dr. DeLaney and colleagues reviewed their entire series of 55 patients who were treated with proton therapy for osteosarcoma between 1983 and 2009.
The median age of the patients was 29 years, and the median follow-up was 27 months.
Twenty-seven patients (49.1%) underwent surgery and had positive surgical margins, and surgeon's notes indicated that five other patients (9.1%) had residual disease. The remaining 23 patients had surgery consisting of biopsy only or minor resection with residual gross tumor.
Twenty-two patients (40%) received proton-based radiotherapy doses between 60 Gy and 70 Gy, and 28 patients (50.1%) received total doses of 70 Gy or more. Five patients (9.1%) received doses below 60 Gy.
Local control rates were 82% at 3 years and 72% at 5 years, and there were no relapses in the 12 patients with grade 1 disease.
Ten patients failed within the treatment field, including eight of 22 patients with osteosarcoma of the bones of the skull. Eleven patients experienced distant failure (10 of these had grade 2 or higher disease).
Disease-free survival was 68% at 2 years and 65% at 5 years, and overall survival was 84% at 2 years and 67% at 5 years.
Twelve patients experienced grade 1 toxicity, 12 patients experienced grade 2 toxicity, and 17 patients experienced grade 3 or 4 toxicity. Two patients died from treatment-related malignancies 1.5 years and nearly 16 years after successful treatment of their osteosarcoma.
"Proton therapy is especially suitable for young patients with osteosarcoma, in whom reductions in the integral dose to nontarget tissue is important to minimize the risk to normal tissue development and of secondary malignancies," the researchers note.
As far as alternatives to proton-based radiotherapy, Dr. DeLaney said, "Patients could get 3D or IMRT (intensity-modulated radiotherapy) photons, which would likely be associated with higher acute and late morbidity, especially in young patients who are the majority of osteosarcoma patients. There is also some experience with radioisotopes such as samarium, but usually not curative."
"Osteosarcomas arising in the axial spine, pelvis, or skull have traditionally been very difficult to treat," Dr. Thomas F. DeLaney from Massachusetts General Hospital, Boston, told Reuters Health in an email. "They require high radiation doses for local tumor control. Protons, with no exit radiation dose beyond the tumor, allow high-dose radiation, in combination with chemotherapy, while sufficiently sparing normal tissue to control some of the challenging osteosarcomas."
The cost of proton-based radiotherapy, Dr. DeLaney said, "is higher in the short term, but may be less expensive than IMRT photons in the long run because of fewer treatment-associated late effects, i.e., cardiac, second tumors, etc."
Dr. DeLaney and colleagues reviewed their entire series of 55 patients who were treated with proton therapy for osteosarcoma between 1983 and 2009.
The median age of the patients was 29 years, and the median follow-up was 27 months.
Twenty-seven patients (49.1%) underwent surgery and had positive surgical margins, and surgeon's notes indicated that five other patients (9.1%) had residual disease. The remaining 23 patients had surgery consisting of biopsy only or minor resection with residual gross tumor.
Twenty-two patients (40%) received proton-based radiotherapy doses between 60 Gy and 70 Gy, and 28 patients (50.1%) received total doses of 70 Gy or more. Five patients (9.1%) received doses below 60 Gy.
Local control rates were 82% at 3 years and 72% at 5 years, and there were no relapses in the 12 patients with grade 1 disease.
Ten patients failed within the treatment field, including eight of 22 patients with osteosarcoma of the bones of the skull. Eleven patients experienced distant failure (10 of these had grade 2 or higher disease).
Disease-free survival was 68% at 2 years and 65% at 5 years, and overall survival was 84% at 2 years and 67% at 5 years.
Twelve patients experienced grade 1 toxicity, 12 patients experienced grade 2 toxicity, and 17 patients experienced grade 3 or 4 toxicity. Two patients died from treatment-related malignancies 1.5 years and nearly 16 years after successful treatment of their osteosarcoma.
"Proton therapy is especially suitable for young patients with osteosarcoma, in whom reductions in the integral dose to nontarget tissue is important to minimize the risk to normal tissue development and of secondary malignancies," the researchers note.
As far as alternatives to proton-based radiotherapy, Dr. DeLaney said, "Patients could get 3D or IMRT (intensity-modulated radiotherapy) photons, which would likely be associated with higher acute and late morbidity, especially in young patients who are the majority of osteosarcoma patients. There is also some experience with radioisotopes such as samarium, but usually not curative."
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