Ewing’s sarcoma can affect people from 5 months old to 60 years old but peaks at 10-20 years of age.1 This type of tumor usually doesn’t affect the Asian or African population and is more predominant in males. Around 16% of bone tumors and 3% of childhood cancers are Ewing’s sarcoma.
Etiology:
There are no known particular causes for Ewing’s sarcoma.1 However, there is a strong relationship with chromosomal translocation. Many patients with Ewing’s sarcoma have translocation effecting chromosomes 11 and 22.
Signs & Symptoms:
The most common presenting symptom of Ewing’s sarcoma is pain and swelling at the region of the tumor. If the mass becomes palpable, there is a high likelihood that the tumor is more advanced and has spread into the surrounding tissues. There may also be symptoms such as shortness of breath, fatigue,weight loss, and a fever.2
Diagnostic Procedures:
Radiographs and computed tomography (CT) scans are used to visualize bone lesions while magnetic resonance imaging (MRI) scans are used to view soft tissue expansion. A bone scan is also used in order to detect possible skeletal metastases.2
Histology:
There are several microscopic patterns, but the diffuse patten is the most common.2
The lobular pattern involves fibrovascular septa separating multicellular aggregates of tumor.
A poor prognosis results when the patient has a filigree pattern, in which the tumor is found in roughly bicellular strands separated by a filmy fibrovascular stroma.
Immunohistochemical analysis is typically needed to identify the true nature of the tumor or confirm a diagnosis.
Most cases show necrosis, pink necrotic cells in the center, and have a high mitotic rate.
Solid tumor clusters are separated by fibrous bands.
Ewing's sarcoma is one of many small blue round tumor cells, therefore, a diagnosis needs to be correlated clinically, radiographically, morphologically, or with molecular findings.
Lymph node drainage:
Lymph node metastases are rare.2
Hematogenous mets frequently occur in the lungs, bones, and visceral organs.
Near by lymph nodes include Lumbar, Iliac, Iguinal, and popliteal
Metastatic spread:
Hematogenous metastases frequently occur in the lungs and other skeletal bones.2 Other common sites involve visceral organs. Lymph node metastases are rare. Nonsymptomatic metastases are usually present at diagnosis. Metastatic symptoms, when present, include multifocal bone pain and shortness of breath.
Grading:
Enneking Staging System for Bone Sarcomas2: Grade 1 (G1), low grade: Parosteal osteosarcoma, endosteal osteosarcoma, secondary chondrosarcoma, fibrosarcoma (low grade), atypical malignant fibrous histiocytoma, giant cell tumor, adamantinoma.
The Enneking Staging System is used for Bone Sarcomas2
Grade (G)
G1, low grade
Parosteal osteosarcoma
Endosteal osteosarcoma
Secondary chondrosarcoma
Fibrosarcoma, low grade
Atypical malignant fibrous histiocytoma
Giant cell tumor
Adamantionoma
G2, high grade
Classic osteosarcoma
Radiation-induced sarcoma
Paget’s sarcoma
Primary chondrosarcoma
Fibrosarcoma
Giant cell sarcoma
Local Extent (T)
T1, intracompartmental
Intraosseous
Parosseous
Intrafascial
T2, extracompartmental
Soft tissue extension
Extrafascial or deep fascial extension
Metastases (M)
M0: no distant metastases
M1: distant metastases present
Radiation side effects:
The effects of radiation therapy on bone are directly related to the dose and treatment volume and adversely related to age at time of therapy.2 Growth abnormalities are evident 6 months and 1 year after treatment in infants and in older children, respectively. Scoliosis after vertebral irradiation is limited and is compensated for by pelvic tilt. Irradiated bone is more prone to infection, fracture, and necrosis because of small-vessel changes.
Prognosis:
For patients with localized Ewing tumors, the five-year survival rate is close to 70%.3 For metastatic tumors, the five-year survival rate is 20% to 30%. If the cancer has spread only to the lungs, the rate is slightly better.
Treatments:
Currently, the treatment of all Ewing's sarcoma (both soft tissue tumors and bone tumors) is the same. Based on the results of a number of clinical trials, the first line treatment is quite standardized and consists of4:
14-17 cycles of chemotherapy, alternating between 2 regimens of drugs
Resection surgery if possible, which frequently involves limb-sparing surgery with prosthetic reconstruction or donor bone grafts if there is bone involvement
Daily radiation treatments for 6 weeks to the primary site may be required if complete surgical resection is not possible
Ewing's sarcoma is an aggressive cancer, and requires 9 months to a year to treat in the best case. If the cancer doesn't respond to "first line treatment" and if there is known disease, the patient may be a candidate for a clinical trial.
TD 5/5:
The TD 5/5 for Ewing Sarcoma is difficult because it can develop in any bone in the body. However, it is most frequently seen in the long bones in the lower half of the body.1 Therefore, there are really no critical organs near the long bones. The TD 5/5 for the femoral head is 52 gray (Gy) and the TD 5/5 for bone is 60 Gy.
Additional images:
Reprinted from International Journal of Radiation Oncology Biology Physics, 2013.5
The images above are from a radiotherapy plan for a patient with a Ewing’s sarcoma of the left pelvis.5 Image A is sagittal slice through the target area at the level of the ovaries. Image B is a coronal reconstruction of the same patient. The right ovary is represented by the blue and the left by the yellow region, including a 3-mm margin allowing for a day-to-day setup variability. The primary tumor and the area of subclinical spread (purple region) are encompassed by the 95% isodose (bold green line) of the prescribed dose (45 Gy in 25 fractions of 1.8 Gy) with a rapid dose falloff at the field edge.
References:
Washington CM, Leaver D. Principles and Practice of Radiation Therapy. 3rd ed. St. Louis, MO: Mosby Elsevier; 2010.
Chao K, Perez C, Brady L. Radiation Oncology Management Decisions. 3rd ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2011.
Wallace WHB, Thomson AB, Saran F, Kelsey TW. Predicting age of ovarian failure after radiation to a field that includes the ovaries. Int J Radiat Oncol Biol Phys. 2005;62(3):738-744. doi:10.1016/j.ijrobp.2004.11.038.
Grade 1 (G1), low grade: Parosteal osteosarcoma, endosteal osteosarcoma, secondary chondrosarcoma, fibrosarcoma (low grade), atypical malignant fibrous histiocytoma, giant cell tumor, adamantinoma.
G2, high grade: Classic osteosarcoma, radiation-induced sarcoma, Paget’s sarcoma, primary chondrosarcoma fibrosarcoma, (high grade), malignant fibrous histiocytoma, giant cell sarcoma.
Grade (G)
Local Extent (T)
Metastases (M)
- 14-17 cycles of chemotherapy, alternating between 2 regimens of drugs
- Resection surgery if possible, which frequently involves limb-sparing surgery with prosthetic reconstruction or donor bone grafts if there is bone involvement
- Daily radiation treatments for 6 weeks to the primary site may be required if complete surgical resection is not possible
Ewing's sarcoma is an aggressive cancer, and requires 9 months to a year to treat in the best case. If the cancer doesn't respond to "first line treatment" and if there is known disease, the patient may be a candidate for a clinical trial.Reprinted from International Journal of Radiation Oncology Biology Physics, 2013.5
The images above are from a radiotherapy plan for a patient with a Ewing’s sarcoma of the left pelvis.5 Image A is sagittal slice through the target area at the level of the ovaries. Image B is a coronal reconstruction of the same patient. The right ovary is represented by the blue and the left by the yellow region, including a 3-mm margin allowing for a day-to-day setup variability. The primary tumor and the area of subclinical spread (purple region) are encompassed by the 95% isodose (bold green line) of the prescribed dose (45 Gy in 25 fractions of 1.8 Gy) with a rapid dose falloff at the field edge.
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