Radiation Oncology/Sarcoma/Chondrosarcoma

Epidemiology

• Heterogenous group of tumors forming cartilagenous tumors
  • If there is evidence of osteoid or bone production, the tumor is classified as an osteosarcoma
• Median age in 3rd to 4th decades; 50% in patients >40
• Distribution:
  • Pelvis (31%)
  • Femur (21%)
  • Shoulder girdle (13%)
  • Diaphyseal portion of long bones
  • Skull base - can be a clinical challenge, since frequently limited resectability
• Clinical presentation
  • Pain is a sign of active growth, and is an ominous sign
  • Otherwise symptoms depend on location
• Radiographic presentation
  • Two distinct patterns
    • Small, well-defined lytic lesion within a narrow zone of transition, with surrounding sclerosis
    • No sclerotic border
  • Endosteal scalloping is a key sign of malignancy

Histologic Subtypes

• Central (76%)
• Peripheral
• Mesenchymal: high rate of metastatic spread
• Dedifferentiated: may resemble a fibrosarcoma or osteosarcoma; highly aggressive
• Clear cell: slow growing, multiple local recurrences
• Most tend to be low grade

Treatment Overview

• Treatment is maximum surgical resection while minimizing functional disability. Decompression of visual and other neural structures, blood vessels, and brain stem should be achieved.
• Adjuvant RT typically indicated in cases of incomplete resection
• No effective chemotherapy at this time

Proton Beam Radiotherapy

• Orsay; 2008 (France)(1996-2006) PMID 18440726 -- "Proton therapy in pediatric skull base and cervical canal low-grade bone malignancies." (Habrand JL, Int J Radiat Oncol Biol Phys. 2008 Jul 1;71(3):672-5. Epub 2008 Apr 25.)
  • Retrospective. 30 children with chordoma (n=26), chondrosarcoma (n=3), and chondroma (n=1). Location in skull base (n=13), skull base with extension to cervical canal (n=12), or cervical canal (n=1). Median age 13.5 years. Surgery followed by photon/proton therapy. Mean total dose 68.4 CGE (54.6-71); mean photon dose 37.4 Gy (30.6-45), mean proton dose 32.1 CGE (20-70.2). F/U 2.2 years
  • Outcome: Local control chordoma 21/26 (81%), chondrosarcoma 3/3 (100%), chondroma 1/1 (100%). 5-year PFS chordoma 77%, chondrosarcoma 100%
  • Toxicity: Grade 3 auditory toxicty 1 patient, Grade 2 pituitary failure 7 patients
  • Conclusion: Well tolerated, excellent local control

• MGH, 1999 - PMID 10555005 -- "Chondrosarcoma of the base of the skull: a clinicopathologic study of 200 cases with emphasis on its distinction from chordoma." Rosenberg AE et al. Am J Surg Pathol 1999 Nov;23(11):1370-8.
  • 200 pts w/ chondrosarcoma tx'd w/ proton/photon radiation as a portion of tx regimen. Pts received 64.2-79.6 CGE (median 72 CGE).
  • 5 yr local control 99%, 10 yr local control 98%.
  • 5 and 10 yr dz specific survival rate both 99%.
  • Conclusion: excellent prognosis w/ aggressive management in contrast to chordoma which has substantially worse prognosis.

• Loma Linda, 1999 (1992-98) - PMID 10470818 -- "Proton radiation therapy for chordomas and chondrosarcomas of the skull base." Hug EB et al. J Neurosurg. 1999 Sep;91(3):432-9.
  • 25 chondrosarcomas (and 33 chordoma) pts tx'd w/ proton beam irradiation after maximal surgery. Dose range of 64.8-79.2 CGE.
  • 5yr OS for chondrosarcoma was 100%. 5yr local control for chondrosarcoma was 92%.
  • Control rates were influenced by brainstem involvement and tumor volume.
  • Chondrosarcoma with better outcomes than chordoma.

• Netherlands, 1998 - PMID 9667567 -- "Intracranial chondrosarcoma: review of the literature and report of 15 cases." Korten AG et al. J Neurol Neurosurg Psychiatry. 1998 Jul;65(1):88-92.
  • Reviewed all cases of intracranial chondrosarcoma in the Netherlands and available data in the literature.
  • Found surgery alone to have a 53% local recurrence rate w/ average time to recurrence of 32 months.
  • Adjuvant charged particle irradiation had local control of 78-91% at 5 yrs, and 5 yr OS of 83-94%.