Radiation Therapy

Introduction

Two mechanisms of action
- production of free radicals
- direct genetic damage

Indications of External beam irradiation

Definitive control (primary malignant bone tumors)
- Ewing sarcoma/primative neuroectodermal tumor
- primary lymphoma of bone
- hemangioendothelioma
- solitary plasmacytoma of bone
Adjuvant to surgical excision
- soft tissue sarcomas
  - may be given pre or post-operatively as adjuvant to surgical excision
  - no difference exists in overall survival and the timing of radiation
Palliative care and impending fracture fixation
- metastatic bone disease
  - needed after fixation of impending/pathologic fractures to reduce overall tumor burden
  - prostate tumors are very radiosensitive
  - breast cancer is 70% sensitive, 30% resistant
  - GI and renal tumors are not radiosensitive

Technique

1 rad = 1 centiGray
Typical dose is 180-200 cGy/day
- radiation is given in "fractions" as radiotherapy is cumulative
- the total dose of therapy is the summation of all the separate fractions given during treatment
Total dose
- < 45 Gray: usually leads to uncomplicated tissue healing
- 45 - 55 Gray: tissue usually heals but with problems
- > 60 Gray: tissue will likely not heal

Complications

Radiation effects on normal tissue
- early effects
  - delayed wound healing
  - infection
  - desquamation
- late effects
  - fibrosis
  - joint stiffness
  - secondary sarcoma (below)
  - fractures (below)
Post-radiation sarcoma
- defined by the development of a sarcoma in a region previously radiated for malignancy
- incidence is ~13%
  - more frequent in patients with prior chemotherapy
- overal patient prognosis is very poor
Post-radiation fractures
- approximately 25% incidence following soft tissue sarcoma resection and external beam irradiation
  - risk factors for post radiation fracture
    - female gender
    - anterior femoral compartment resection
    - age
    - periosteal stripping
    - radiation dose
    - osteoporosis

TAG

(OBQ10.182) A 63-year-old female sustains a subtrochanteric femoral fracture after a fall in her home. Five years ago she underwent resection of a left thigh leiomyosarcoma with adjuvant radiotherapy. All the following are known risk factors for development of pathologic fracture post radiotherapy EXCEPT: Topic

Review Topic

1. Female
2. Age
3. Dose of radiotherapy
4. Periosteal stripping during sarcoma removal
5. Adjuvant chemotherapy

PREFERRED RESPONSE ▶

DISCUSSION: The Level 4 study by Holt et al found a 26% incidence of postradiation fracture in 374 patients following combined surgical resection and external beam irradiation of soft tissue sarcomas. They also found that fracture risk was increased in females, patients older than 50 years of age, and those with higher doses of irradiation (>60 Gy). The Level 4 study by Lin et al of 205 patients found a 29% incidence of fracture at 5 years followup. They found that periosteal resection was a risk factor for fracture occurrence. The use of chemotherapy as an adjuvant treatment has not been shown to increase the risk of post-radiation fracture. The approximate calculated risk of a femoral fracture for this patient is 25%.

REFERENCES:

1. Holt GE, Griffin AM, Pintilie M, Wunder JS, Catton C, O'Sullivan B, Bell RS. Fractures following radiotherapy and limb-salvage surgery for lower extremity soft-tissue sarcomas. A comparison of high-dose and low-dose radiotherapy. J Bone Joint Surg Am. 2005 Feb;87(2):315-9. PMID:15687153 (Link to Abstract)

2. Lin PP, Schupak KD, Boland PJ, Brennan MF, Healey JH. Pathologic femoral fracture after periosteal excision and radiation for the treatment of soft tissue sarcoma. Cancer. 1998 Jun 15;82(12):2356-65. PMID:9635528 (Link to Abstract)

Question Authors:

Michael Hughes MD,

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Level of Evidence 4 (Case Series)

Holt GE, Griffin AM, Pintilie M, Wunder JS, Catton C, O'Sullivan B, Bell RS. Fractures following radiotherapy and limb-salvage surgery for lower extremity soft-tissue sarcomas. A comparison of high-dose and low-dose radiotherapy. J Bone Joint Surg Am. 2005 Feb;87(2):315-9. PMID:15687153 (Link to Abstract)
Lin PP, Schupak KD, Boland PJ, Brennan MF, Healey JH. Pathologic femoral fracture after periosteal excision and radiation for the treatment of soft tissue sarcoma. Cancer. 1998 Jun 15;82(12):2356-65. PMID:9635528 (Link to Abstract)

Textbooks

Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012

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