# Radiation Oncology/Sarcoma/Chondrosarcoma

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## 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

## Radiotherapy

* MDACC; 1982 (1961-76) PMID 6806219 -- "Fifteen year radiotherapy experience with chondrosarcoma of bone." (McNaney D, Int J Radiat Oncol Biol Phys. 1982 Feb;8(2):187-90.)
** Retrospective. 20 pts treated with curative intent (11, definitive RT; 3 post-op RT; 3 RT + chemo; 3 recurrent after surgery). RT doses 4000 - 7000 cGy (1000 / wk) using photons and/or neutrons.
** Sites: 13 pelvis, 4 spine, 2 distal femur, 1 H&N
** Subgroups:
*** RT alone: 5 of 11 (45%) alive without progressive local disease (at median 30 months). OS 54% at 30 months. Median dose 6600 cGy. 4 pts treated with mixed photons + neutrons. The rest treated with photons alone.
*** Post-op: 2 of 3 alive w/o progressive disease at 44 and 52 months. Dose range 4500-6000 cGy.
*** RT+chemo w/o surgery: 2 of 3 alive w/o progressive disease at 15 and 29 months. Dose range 4000-6400 cGy.
*** RT for recurrence: 2 of 3 alive w/o progressive disease at 19 and 77 months. Dose range 6200-7000 cGy.
** 11 of 20 (55%) show no evidence of progressive local disease at median 30 months. Two additional patients surgically salvaged after RT failure; overall survival rate 65% (13/20).
** Severe complications in 5 pts: 3 foot drop, 1 subcutaneous fibrosis, 1 eye enucleation.
* Princess Margaret; 1980 (1958-76) PMID 7379008 -- "Radiotherapy of chondrosarcoma of bone." (Harwood AR, Cancer. 1980 Jun 1;45(11):2769-77.)
** Retrospective. 31 pts (20 pts - definitive RT, 11 pts - palliative).
** Conclusion: "Our experience shows quite clearly that chondrosarcoma of bone can no longer be classified as a radioresistant tumor."

## 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%.