Ewing Family of Tumors
James Ewing first described Ewing sarcoma in 1921 after observing radiosensitivity in a subgroup of bone tumors. In the early 1980s, Ewing sarcoma and the peripheral primitive neuroectodermal tumor were both found to contain the same reciprocal translocation between chromosomes 11 and 22, t(11;22). Later that decade, similar patterns of biochemical and oncogene expression were observed. These tumors were categorized as the Ewing sarcoma family of tumors because of the shared translocation and the similar cellular physiology. The Ewing sarcoma family of tumors includes Ewing sarcoma, peripheral primitive neuroectodermal tumor, neuroepithelioma, atypical Ewing sarcoma, and Askin tumor (tumor of the chest wall). The tumors in the Ewing sarcoma family are treated similarly on the basis of their clinical presentation (eg, metastatic or localized) rather than their histologic subtype.
Tumors in the Ewing sarcoma family are thought to derive from cells of the neural crest, possibly postganglionic cholinergic neurons. The exact cell of origin of the Ewing sarcoma family of tumors is unknown. Research is ongoing to further characterize the biology of the EWS-FLI1 fusion protein and its role in transformation, cell growth, and chemosensitivity. The focus of most research is the fusion protein generated from t(11;22).
Translocation t(11;22) or one of a series of related translocations occurs in more than 95% of the Ewing sarcoma family of tumors. Some argue that, without a translocation, the tumor does not belong to the Ewing sarcoma family. This translocation joins the Ewing sarcoma gene EWS on chromosome 22 to a gene of the ETS family, friend leukemia insertion (FLI1) on chromosome 11 (ie, t[11;22]). The EWS-FLI1 fusion transcript encodes a 68-kDa protein with 2 primary domains. The EWS domain is a potent transcriptional activator, whereas the FLI1 domain contains a highly conserved ETS DNA-binding domain. The EWS-FLI1 fusion protein thus acts as an aberrant transcription factor. EWS-FLI1 transforms mouse fibroblasts, and this transformation requires both the EWS and the FLI1 functional domains to be intact. Therefore, the EWS-FLI1 fusion protein is implicated in the pathogenesis of the Ewing sarcoma family of tumors. However, no data regarding the cause of the translocation are available. Downstream targets that are responsible for EWS-FLI1 transformation are currently under study.
In any individual patient, t(11;22) fuses one of many observed combinations of exons from EWS and FLI1 to form the fusion message. The most common combination is EWS exon 7 fused to FLI1 exon 6 (type 1 translocation), which occurs in approximately 50-64% of tumors of the Ewing sarcoma family. Retrospective analyses showed that patients who have localized tumors with the 7/6 fusion have a 4-year survival rate of 70%, whereas patients with the other variants have a 4-year survival rate of 20%. This difference may, at least in part, be due to different potencies among the variants in their ability to activate gene transcription.
Frequency United States
The annual incidence of Ewing sarcoma family tumors from birth to age 20 years is 2.9 cases per million population. Approximately 10% of patients are aged 20-30 years. Cases occurring later than this are infrequent.
The survival of patients with Ewing sarcoma family tumors highly depends on the initial manifestation of the disease. Approximately 80% of patients present with localized disease, whereas 20% present with clinically detectable metastatic disease, most often to the lungs, bone, and/or bone marrow. The overall survival rate is 60%; however, for patients with localized disease, the survival rate approaches 70%. Patients with metastatic disease have a long-term survival rate of less than 25%.
The incidence in whites is at least 9 times higher than that in blacks. This finding is in contrast to what is observed osteosarcoma, which has a relatively equal racial distribution. African countries report similar incidences, with a paucity of Ewing sarcoma family of tumors.
The incidence of Ewing sarcoma family tumors in female individuals is 2.6 cases per million population. The incidence in male individuals is 3.3 cases per million population.
Incidence peaks in the late teenage years. Overall, 27% of cases occur in the first decade of life, 64% of cases occur in the second decade of life, and 9% of cases occur in the third decade of life.
- Patients usually present with pain.
- Patients often have a palpable mass.
- Patients with lesions of the long bones can present with a pathologic fracture.
- Back pain may indicate a paraspinal, retroperitoneal, or deep pelvic tumor.
- Systemic symptoms of fever and weight loss can also occur and often indicate metastatic disease.
- Tumors of the Ewing sarcoma family can occur in virtually any location. Careful examination of painful sites with inspection and palpation is critical.
- Because patients can present with disease close to bone, tumors can result in neuropathic pain. Therefore, a comprehensive neurologic examination to evaluate asymmetric weakness, numbness, or pain is critical.
- Patients with lung metastases can present with asymmetric breath sounds, pleural signs, or rales.
- Patients with clinically significant bone marrow metastases can present with petechiae or purpura due to thrombocytopenia.
- The cause is unknown.
- Cases are thought to be sporadic. However, the incidence of neuroectodermal and stomach malignancies is increased among family members of patients with tumors of the Ewing sarcoma family.
- Ewing sarcoma family tumors are rarely reported after the treatment of another neoplasm (second malignancy).
Further Inpatient Care
- Chemotherapy can be administered on an inpatient or outpatient basis, depending on patient tolerance and proximity to the hospital.
- Patients often develop episodes of fever while neutropenic, resulting in 3- to 7-day hospitalizations between cycles of chemotherapy.
Further Outpatient Care
- Chemotherapy care and follow-up
- Most patients require RBC and platelet support starting approximately 2 months after the start of therapy and continuing to the completion of therapy. Although G-CSF is given for neutrophil support, biweekly CBC counts are necessary.
- A full physical examination is required before each cycle of chemotherapy and any time suspicious signs or symptoms arise between cycles. Suspicious signs include signs similar to those observed at presentation, as well as unexplained fever or pain.
- Primary and metastatic sites are evaluated approximately every 10-12 weeks during therapy and every 3-4 months during the first year after therapy.
- Reevaluations are spaced out gradually for 5-6 years after the completion of therapy. At that time, no further scanning is indicated; however, the patient should have annual follow-up visits to monitor function of the primary site and late effects of therapy.
- Long-term follow-up
- Late effects from chemotherapy require regular follow-up with a provider trained to evaluate the such sequelae.
- Recurrence of primary disease is the major risk in the first 10 years after diagnosis.
- Second malignancy occurs in approximately 1-2% of patients beginning after 5 years after diagnosis. The most common second malignancy is acute myeloid leukemia.
- Therapeutic toxicities to the heart and kidneys and to the nervous, endocrine, and mental systems should be monitored in patients who had acute toxicity and in those who developed symptoms after therapy.
- Patient care during chemotherapy is generally under the direct supervision of the pediatric oncologist. The primary care physician should be kept informed about the patient's progress and complications.
- After therapy is completed, the primary physician should increase his or her involvement in patient care.
- No prevention methods are known.
- Chemotherapy complications
- Vincristine primarily causes neuropathy, including constipation, myalgias, arthralgias, and cholestasis.
- Doxorubicin causes myocardial dysfunction and pancytopenia.
- Cyclophosphamide causes pancytopenia and a dosage-dependent hemorrhagic cystitis.
- Ifosfamide is similar to cyclophosphamide, although it is associated with an increased incidence of hemorrhagic cystitis, which requires the use of mesna. Patients near the end of therapy occasionally develop the Fanconi syndrome of electrolyte wasting.
- Etoposide can result in pancytopenia as well as anaphylactic reactions, and it is implicated in the development of second malignancies, particularly acute myelogenous leukemia.
- In general, combination chemotherapy results in alopecia, nausea, vomiting, and, occasionally, diarrhea. The nutritional and psychologic statuses of patients undergoing this therapy must be closely monitored.
- Surgical complications>
- Surgical complications generally include infection and bleeding.
- Specific complications are related to the site of surgery and to the patient's overall condition at the time of surgery.
- Radiation complications
- Complications of radiation therapy are a direct result of the sites of radiation.
- Patients who receive large pelvic doses of radiation often have increased problems with pancytopenia, malnutrition, and diarrhea.
- Radiation increases the likelihood of second malignancies, particularly in the radiation field.
At this time, the only significant factor that determines the prognosis is the presence or absence of metastatic disease.<
- Any patient with a malignancy needs extensive education, as does their family.
- For the patient, education includes age and developmentally appropriate information about their disease and its therapy. Patients should be informed about their specific disease and prognosis. Education also includes information about expected complications, particularly fever and its management.
- Chemotherapy involves a group of medications with clear and notable risks, both immediate and long-term.
- Obtaining informed consent is required before therapy if the patient will be enrolled in a clinical trial. If no appropriate trial is accruing patients, the oncologist refers to the most recent clinical trial to determine the best therapeutic regimen. A consent form that includes the recommended agents and their adverse effects should be strongly considered in these circumstances.
- Because these tumors are rare, they are often not considered in a differential diagnosis until biopsy reveals a small, round, blue cell tumor.
- Malignancy is usually in the differential diagnosis before biopsy. For this reason, consultation with a pediatric oncologist is critical.
- These tumors should be considered in the differential diagnosis if a patient aged 10-30 years has a soft tissue or bony mass that causes the physician to consider a neoplasm.