Ewing’s sarcoma is a rare cancer that develops within the bone marrow. It may arise in almost any bone; typically, however, half of all Ewing’s sarcomas are in the thighbone (femur), the shinbone (tibia) or the upper arm (humerus). The disease most commonly strikes children ten to twenty years old, but also may occur in both older and younger patients, with a slight predilection for boys.
Pain and then swelling are usually the first symptoms. Fever and other signs of infection such as a high white blood cell count may lead to an initial incorrect diagnosis of osteomyelitis, an inflammation of the bones caused by a bacterial or fungal infection. X rays tend to show extensive involvement of the solid outer part of the bone (the cortex), with new bone formation in the protective lining of the bone’s outer surface, resulting in an onionskin appearance.
Often a large soft-tissue mass can also be seen. Occasionally other bones may be affected simultaneously, giving the impression that the disease originates in more than one site. Metastasis to the lungs is common.
Radiation therapy is the most common treatment for Ewing’s sarcoma, although surgical removal is performed in some cases, depending upon location of the tumor. Chemotherapy usually is given along with the radiation therapy. More recently, however, an experimental treatment has been developed to study the usefulness of chemotherapy alone as the initial therapy, followed in two or three months by surgery or radiation therapy or both.
Radiation therapy in any type of bone cancer must be given with extreme care and precision to avoid destruction of healthy tissue. The bone marrow, in particular, is very sensitive to irradiation. Once started, however, treatment should be continued for the full predetermined course despite any quick disappearance of the tumor and symptoms—something that occurs frequently. The total required radiation dose is about 6,000 to 6,500 rads delivered over six to seven and a half weeks in combination with several anticancer drugs. The initial 4,000 rads is delivered to the primary tumor, surrounding soft tissue, and the entire inner (medullary) portion of the affected bone. The final 2,000 to 2,500 rads are directed intensively to the tumor itself. The treatments are generally given daily. Antinausea drugs may be given to help prevent nausea and vomiting, which may occur as side effects of the radiation therapy and/or anticancer drugs.
During the actual radiation treatments, the patient is usually placed in special restraining devices. Many patients find this a frightening aspect of undergoing radiation therapy, but the devices are important to prevent any movement and to ensure that the radiation is correctly beamed.
In addition, a program of active exercise for all treated joints should be instituted at the start of therapy. The degree of damage to the solid outer (cortical) bone by the tumor growing from the inner (medullary) area determines the type of exercises that should be undertaken and also whether or not the bones should bear any weight during the course of treatment. If proper precautions are followed during radiation therapy, satisfactory use of the bone usually will be regained.
Recent studies have been undertaken to determine whether the total radiation dose can be reduced if chemotherapy is used as the main treatment. This is important because large radiation doses may cause later complications, even though the disease is cured. These studies show that in most patients, three months of chemotherapy destroys a large portion of the tumor. What remains is then removed by surgery, and the site is treated by radiation therapy. This approach allows the total radiation dose to be reduced to about 4,000 rads. It should be noted, however, that this approach is still considered experimental and is available in only a few centers. Furthermore, it is suitable for only selected sites, such as the pelvis or ribs.
When Ewing’s sarcoma occurs in children under the age of seven years and affects the arms or legs, the best treatment is immediate amputation. Radiation will inevitably retard the growth of the limb, while the healthy limb will continue to develop normally. Eventually there would be a tremendous discrepancy in limb length, requiring amputation. Rehabilitation is more effective if the amputation is performed early rather than later, even though most parents find it difficult initially to accept this concept. In addition, this approach has an added advantage in that it usually avoids radiation therapy, which may have even more pronounced later complications when administered to young children.
Chemotherapy of Ewing’s sarcoma may entail giving drugs, such as dactinomycin or doxorubicin, which worsen the adverse effects of radiation therapy. Therefore in any combined approach using these drugs, considerable skill on the part of the treating physicians is required to ensure that the chemotherapy and radiation are properly integrated. (Other drugs, such as vincristine or cyclophosphamide, which do not compound the adverse effects of radiation, may also be used.) In addition to the combined therapy, anticancer drugs are usually administered for another one to two years to destroy any metastases to other parts of the body.
Although the treatment for Ewing’s sarcoma may be complicated and difficult for the patient, the results justify the effort. Following these combined approaches to treatment, 60 to 70 percent of patients with Ewing’s sarcoma can expect to be cured, defined as being well and free of disease five years later. Although late metastases may still occur, this is a dramatic improvement over the past. Before the advent of chemotherapy, only about 5 percent of the patients could expect to be cured.
Unfortunately, the outlook is not as optimistic when Ewing’s sarcoma has metastasized. In such instances, a combination of treatments will be used and may include experimental protocols. Radiation therapy may be administered to the tumor sites. Chemotherapy usually follows for one to two years, and regular physical and X-ray examinations are important in the follow-up.
Studies involving patients treated with this intensive regimen have yielded a 30 to 40 percent symptom-free survival at a median time of thirty-four months a marked improvement over the past, but one that will require more time to determine whether or not the patients are indeed cured. Following treatment, patients should undergo X rays of the chest as well as the cancer site at regular intervals of one to six months for five years, and annually thereafter. Any unusual symptoms, particularly at the site of the radiation treatments, should be reported promptly to a doctor.