Key Terms: Adjunctive therapy, Beta-glucan, Bioavailability, Hedyotis diffusa, Median survival time, Non-small cell cancer, Scutellaria barbata, Stage I non-small cell cancer.
Definition
The superior vena cava is a large vein in the chest that drains the blood from the upper body back to the heart. Compression or occlusion (blocking off) of this vein creates superior vena cava syndrome.
Description
When the superior vena cava (SVC) becomes compressed or occluded, the blood from the upper body cannot drain back to the heart properly. This creates suffusion (the spreading of bodily fluids into surrounding tissue) which causes varying degrees of airway obstruction, swelling and cyanosis (purple discoloration due to lack of oxygenation) of the face, neck, arms and chest area.
Causes
Cancer is the most common cause of superior vena cava Syndrome. Lung cancer, lymphoma, breast cancer, and germ cell tumors of the chest are commonly associated with SVC syndrome. Any cancer that invades or constricts the blood vessels in the chest can cause SVC syndrome. Other non-cancer causes of SVC Syndrome are thyroid goiter, fungal infections, pericardial constriction, aortic aneurysm, and any other disease that creates swelling in the mediastinum (organs and vessels of the chest). Occasionally, SVC syndrome can be caused by a central vein catheter (an IV catheter that is placed into central circulation with its tip in the superior vena cava), which may cause a thrombosis (blockage) of the SVC.
Symptoms
Patients with superior vena cava syndrome (SVC syndrome) might experience facial swelling causing the shirt collar to feel tight, shortness of breath, coughing, a change of voice, or confusion. A patient might also notice distention or enlargement of veins near the surface of the skin. The development of these signs and symptoms is usually a gradual process taking up to four weeks from onset of symptoms to diagnosis.
Diagnosis
The physician diagnoses SVC syndrome by starting with a complete patient history and physical examination. The physician will ask about onset of symptoms and time-frames of symptom development. The physician will recommend a chest x ray and a computed tomography scan to visualize the chest area in order to confirm the presence of SVC syndrome. The physician may also order venous patency (flow of blood through the vein) studies using contrast dye and scanning techniques. The physician may order a scan done in a Magnetic resonance imaging (MRI) lab, ultrasound lab, or in nuclear medicine to help assess the cause of the superior vena cava syndrome. These tests help the physician identify the site and nature of the obstruction. If cancer of the bronchi is suspected, the patient should also anticipate other testing such as sputum collection, bronchoscopy, and biopsy of the suspected cancer site. These tests are very important to the oncologist (a physician who specializes in the treatment of cancer), because they will help to identify the disease, determine the stage, and hence the appropriate course of treatment.
Risks
Many patients have the symptoms of superior vena cava syndrome for more than a week before seeing their doctor. Sometimes the diagnosis of SVC syndrome is the first sign that there is cancer present in the body (only 3% to 5% of patients with SVC syndrome do not have cancer). Most patients with SVC syndrome do not die from the syndrome itself, but from the underlying disease, and the extent of the cancer invasion causing the syndrome. Physicians consider the presence of superior vena cava syndrome a life-threatening oncologic medical emergency when there is tracheal (airway) obstruction present. Further, if there is extensive suffusion causing swelling in the vessels in the brain, the patient's condition can rapidly deteriorate. Once the diagnosis of SVC syndrome is made, the physician will immediately commence determining the cause of the syndrome to avoid or minimize these risks.
Treatment
There are several treatment options to alleviate the symptoms of SVC syndrome. The feasibility of these options depends on the primary cause of the obstruction, the severity of the symptoms, the prognosis of the patient, and the patient's preferences and ultimate goals for therapy. The physician will need to determine the histology (cellular origin) of the obstructing cancer before proceeding with SVC syndrome treatment. Unless there is airway obstruction or swelling in the brain, treatment of SVC syndrome can be delayed to determine the stage of the underlying disease.
Medical management of SVC syndrome includes elevating the head, using steroids to minimize swelling, and diuretics to remove fluid from circulation. Some patient may develop collateral circulation (development of smaller vessel branches to assist with the excess fluid load on the SVC) and not need further treatment.
Chemotherapy is used on lymphomas or small cell lung cancers because they are sensitive to the drugs. Rapid initiation of chemotherapy in these situations can dramatically reduce the unpleasant symptoms of SVC syndrome in most patients. When chemotherapy is not the best choice for the cancer type, radiation therapy can provide some relief from symptoms.
Questions to Ask Your Doctor
- Which risk group has my child been assigned to?
- What treatments would you recommend for a child in that group, and why would you recommend them?
- Is my child eligible for any current clinical trials for children with SPNETs?
- Would you recommend any of the treatments currently considered experimental?
- If the tumor recurs, what is my child's life expectancy? What can I do to make the remaining time as pain-free and enjoyable as possible?
Other treatment options include thrombolysis where a fibrolytic agent (agent that breaks down a thrombus or clot) is injected into the obstructed SVC. This option is used when it is determined that the obstruction is inside the vein. Stent placement (placing a sterile mesh tube inside the SVC to keep the vessel open) has been used successfully in some patients, but may require ongoing anticoagulation therapy after placement. Finally, surgical bypass of the obstructed SVC is a possible option for some patients, however the procedure is extensive and the patient must have appropriate healthy veins to graft to the affected area.
Resources
Periodicals
Abner, A. "Approach to the Patient who Presents with Superior Vena Cava Obstruction." Chest 103, suppl. 4 (1993): 394–7s.
Baker, G. L., and H. J. Barnes. "Superior Vena Cava Syndrome: Etiology, Diagnosis, and Treatment." American Journal of Critical Care 1 (1992): 54–64.
Chan, R. H., A. R. Dar, E. Yu, et al. "Superior Vena Cava Obstruction in Small-Cell Lung Cancer." International Journal of Radiation Oncology, Biology, Physics 38, no.3 (1997): 513–20.
Dyet, J. F.; A. A. Nicholson, and A. M. Cook. "The Use of the Wallstent Endovascular prosthesis in the Treatment of Malignant Obstruction of the Superior Vena Cava." Clinical Radiology 48, no. 6 (1993): 381–5.
Schraufnagel, D. E.; R. Hill, J. A. Leech, et al. "Superior Vena Caval Obstruction: Is it a Medical Emergency?" American Journal of Medicine 70, no. 6 (1981): 1169–74.
—Molly Metzler, R. N., B. S. N.
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