Superior Vena Cava Syndrome
The treatment of SVCS depends on the etiology of the obstruction, the severity of the symptoms, the prognosis of the patient, and patient preferences and goals for therapy. Radiation therapy or chemotherapy should be withheld until the etiology of the obstruction is clear. The treatments discussed here focus on SVC obstruction caused by a malignant tumor. Since the treatment of malignant obstruction may depend on tumor histology, a histologic diagnosis, if not made earlier, should be made prior to initiation of treatment. Unless there is airway obstruction or cerebral edema, there appears to be no detriment in outcome when treatment is delayed for the assessment.[1,11,12,13,14,15] The following treatment approaches can be used for SVCS.
A patient with sufficient collateral blood flow and minimal symptoms may not need treatment. If the lesion is above the azygous vein or if the onset of SVC occlusion is slow enough to allow sufficient collateral circulation, the symptoms and signs may stabilize and the patient may be comfortable enough to forego further therapy. Short-term palliation of a symptomatic patient who does not want aggressive treatment may be achieved by elevating the head and using corticosteroids and diuresis. There are no definitive studies that prove the effectiveness of steroids, although they are potentially useful to treat respiratory compromise. Diuretics may give symptomatic relief of edema but can ultimately cause systemic complications, such as dehydration.[9,16]
If the obstruction of the SVC is caused by a tumor that is not sensitive to chemotherapy, radiation therapy should be given. Treatment with larger fractions of radiation is thought to be beneficial in developing a rapid response. One study shows, however, that there is no obvious need for large radiation fraction sizes for the first few radiation treatments as was previously believed. Many fractionation schemes have been used, with doses ranging from 30 Gy in 10 fractions to 50 Gy in 25 fractions. Relief of symptoms in small cell lung cancer is reported to be 62% to 80%, whereas in non-small cell lung cancer, approximately 46% of the patients experienced symptomatic relief.[2,18] In one study, more than 90% of the patients achieved a partial or complete response with a 3-week regimen of 8 Gy given once a week for a total dose of 24 Gy.
Chemotherapy is the treatment of choice for sensitive tumors such as lymphoma or small cell lung cancer. SVCS does not appear to be an independent prognostic factor, and its presence should not change the treatment approach. Rapid initiation of chemotherapy can result in complete and partial response rates of the SVCS of more than 80% in small cell lung cancer patients.[2,18]