At some stages of cancer management, it may be necessary to perform certain interventions which does not cure the cancer, but can facilitate the main treatment and ease the patients complaints such as pain or bleeding. These interventions are qualified as “palliative” and have the potential to obviate the symptoms of the patients, correct their psychological status and increase their quality of life. Below are the most commonly performed palliative interventions in oncology.
1.Percutaneous biliary drainage and stenting: In many types of cancer, bile ducts (channels) become obstructed due to tumors located in or near the liver (biliary obstruction). It is very important to overcome this obstruction because:
In patients with biliary obstruction, typical symptoms include jaundice, pale stool, dark urine and indigestion. Blood tests may reveal an increase in bilirubin levels and liver enzymes. Ultrasound generally shows enlargements of the bile ducts.
The most simple way of overcoming the biliary obstruction is to put a catheter into the bile ducts percutaneously and attach it to a plastic bag outside the body (biliary drainage). In this technique, problems such as jaundice, itching and cholangitis can be relieved and the patient can start receiving chemotherapy. However, since the bile can not flow into the small bowel, the patient may still have indigestion, develop fatigue due to chronic fluid loss and the necessity to carry a plastic bag may decrease the patient’s life quality. For this reason, it is preferable to reopen the obstructed bile duct by putting a stent to let the bile flow into the bowel. To do this, first a needle is percutaneously placed into the bile ducts and films are taken to see the location of the obstruction. Then, the obstruction is passed by a guidewire and over this guidewire, the obstruction is reopened by using a balloon and stent. In this way, not only the obstruction is obviated but also the bile is diverted again into the small bowel, instead of to a plastic bag outside the body.
2. Percutaneous drainage of pleural or abdominal fluids:
In certain cancer types, fluid may accumulate around the lungs (pleural fluid) or in the abdomen (ascites). When this fluid reaches a certain amount, it may cause symptoms such as pain, fullness and shortness of breath. In these cases, drainage is generally necessary. The easiest way to drain this fluid is to put a catheter into the chest or abdomen and divert the fluid into a plastic bag outside the body. This catheter may stay in place for a long time unless it is obstructed or infected. In these cases, it may be exchanged with a new catheter easily.
3. Percutaneous nephrostomy and double-J stenting:
In cancers located in the lower abdomen, urine channels (ureters) between the kidneys and the urine bladder may be obstructed by the tumor. As a result, the urine can not flow into the bladder and accumulate in the kidney, causing them to swell and deteriorate their function by time. To prevent this, the easiest way is to put a catheter percutaneously into the kidney and drain the urine into a plastic bag outside the body (nephrostomy).
In nephrostomy, the kidney function is preserved, but the patient has to live with a plastic bag, which may decrease his/her quality of life. For this reason, it is preferred to put a special plastic catheter (double-J stent) between the kidney and bladder. In this way, the urine flows into the bladder and is disposed by the patient with urination, as in a normal individual. Double-J stents can be implanted by interventional radiologists, percutaneously via the kidney, or by urologists, endoscopically via the bladder. However, in obstructions due to cancer, radiologic implantation is more likely to be successful.
4. Nerve Blocks:
In cancers located in the abdomen, tumors may attack the nerves and cause severe pain. The pain is first treated with standart pain killers and narcotic analgesics but sometimes they may not be sufficient. In such cases, clusters of nerves (ganglions or ganglia) in the painful region can be ablated to stop or decrease the pain.
In oncology, the most commonly performed nerve block is the celiac ganglion block. Celiac ganglia are located behind the head of pancreas. When these ganglia are blocked, severe pain due to cancers of nearby organs such as pancreas and stomach may be obviated or decreased. To do this, 1-2 tiny needles are percutaneously placed and advanced to the ganglia. After a test injection with a local anesthetic, the ganglia are destroyed with chemical ablation using alcohol or phenol. The block can diminish or obviate the pain in most patients, although in about 1/3 of the patients it may not be successful. The side effects of the celiac ganglion block are diarrhea and hypotension. These may last for a few days after the procedure and disappear spontaneously in most cases.
Another commonly performed nerve block in abdominal cancers is the hypogastric ganglion block. In this block, a tiny needle is percutaneously advanced to the front of the 5th lumbar vertebra, where the hypogastric ganglion is located, and then chemical ablation is performed in the same manner with alcohol or phenol. This ganglion block may be helpful in the pain due to cancers of the pelvic organs such as prostate, uterus, cervix, bladder and rectum.
5. Cementoplasty and vertebroplasty:
Many cancer types metastasize to bones at a certain stage of the disease. Since metastases destroy the healthy bone tissue, the bone becomes weak and prone to fractures. Besides, the rapidly growing tumor may irritate the nerves located in the bone and create severe pain. The weakened bone may be easily broken spontaneously or due to minor traumas (pathologic fracture). These fractures may also cause pain, but more importantly, they may compress the spinal cord and nerves, which may result in serious neurological problems.
Certain hematological cancers like multiple myeloma stimulates the cells that destroy the bone tissue. As a result, bones are weakened, and there may be compression fractures in the weight-bearing bones such as vertebras, which may cause pain and neurological problems.
In such cancer patients, cementoplasty or vertebroplasty may reduce the pain and strengthen the bone. For this, a needle is placed into the bone under imaging guidance and a special “cement” is injected to obviate pain and increase the resistance of the bone. The cement, which is in the fluid form during the injection, becomes hard in the bone in a couple of minutes. The cement destroys the nerves that cause pain and also makes the bone harder. As a result, the pain decreases or disappears and the bone becomes resistant to fracture.
Injection of cement into a bone is in general called “cementoplasty”. A special form of cementoplasty is “vertebroplasty” because it is done to vertebras (backbone). In vertebroplasty, the needle is advanced through the pedicle of the vertebra into its body and the cement is injected carefully. The whole procedure must be performed under fluoroscopy, or preferably, under cone beam CT guidance, because the needle passes very near to critical structures such as the spinal cord.
It must be emphasized that cementoplasty or vertebroplasty are not curative but palliative treatments. They do not kill the tumor but they can obviate the pain and protect the bone from fracture. Cementoplasty and vertebroplasty can also be combined with percutaneous ablation, which can kill the tumor tissue. To do this, first a large needle is inserted into the tumor. Then, through this needle, the ablation needle is placed into its center. Later, the tumor is ablated using radiofrequency, microwave or cryoablation. After that, the ablation needle is removed and the cement is injected into the ablated tumor tissue. In this way, not only the cementoplasty or vertebroplasty are performed but also the tumor tissue is killed.
In cementoplasty, vertebroplasty and concomitant percutaneous ablation, the experience of the physician and the quality of the image guidance are very important. Especially in vertebroplasty/percutaneous ablation procedures, cone beam CT, which can combine fluoroscopy and CT, may significantly increase the safety and success of the intervention.
6. Portal vein embolization:
In some liver cancers, tumors are located only in the right lobe, and if the right lobe could be removed surgically the patient would have a chance of cure. However, the left lobe of the liver is normally smaller than the right lobe and its volume varies from person to person. Therefore, if the right lobe is removed, the remaining left lobe may be insufficient in some patients. This situation can be predicted by calculating the volumes of the right and left lobe with CT before the surgical operation. If the patient has a small left lobe, its volume can be increased by embolising the portal vein of the right lobe (portal vein embolization). Since the portal vein is the main feeder of the normal liver tissue, the right lobe, where the tumors are located, becomes smaller after the embolization and, to compensate for this, the left lobe becomes larger. After the left lobe has become sufficiently large, the right lobe can be safely removed with surgery.
For portal vein embolization, a catheter is percutaneously placed into the right portal vein under ultrasound guidance, and various occluding materials such as coils, particles or glue are injected into the right portal vein. After the embolization, it may take several weeks or months for the left lobe to enlarge sufficiently. During that time, to prevent tumor growth, other transarterial treatments such as radioembolization and intraarterial chemotherapy can be applied to the tumors located in the right lobe. In this way, both the right lobe and its tumors can be made smaller until the tumor-free left lobe reaches the sufficient volume for the operation.
7. Reopening of the occluded vessels:
In cancer, blood clot may occur in the vessels due to the effect of both the tumor and also the treatment (chemotherapy). The clot generally occurs in the veins, and mostly, in the leg veins, which is then called deep vein thrombosis (DVT). In DVT, the leg becomes swollen and painful. The clot that formed in the leg veins may go to the lungs via circulation and cause pulmonary embolism. Pulmonary embolism may lead to difficulty in breathing and sometimes even to death.
DVT can be rapidly and effectively treated by putting a catheter percutaneously into the clotted vein and injecting thrombolytic drugs directly into the clot. In this way, the clotted vein is reopened and complications like pulmonary embolism can be prevented. Sometimes, the vessels may be obstructed not by the clot but by the direct compression of a tumor. In this case, they can be reopened by balloon dilatation and by putting a stent across the obstruction.
8. Embolization of the bleeding vessels:
In some patients, the cancer cells attack the vessels and destroy their walls, causing dangerous bleedings. In such a case, instead of a surgical operation which is more dangerous in a bleeding patient, the bleeding vessel can be identified with angiography and treated with embolization in the same session. Once the vessel is occluded with embolization, the bleeding stops rapidly. Embolization can be repeated if bleeding recurs. Embolization of the bleeding vessels is mostly performed for bronchial bleeding due to lung tumors (bronchial artery embolization). It is also frequently performed to stop bleedings due to tumors located in the neck, kidney, stomach and bowels.
9. Ablation and transarterial treatments for pain palliation:
In oncology, percutaneous ablation and transarterial treatments are normally used to kill the cancer tissue. In some patients, these treatments can also be employed to provide relief for patient’s complaints, mostly for pain. Percutaneous ablation techniques such as radiofrequency, microwave and cryoablation are particularly useful in the pain due to soft tissue and bone tumors. In some situations, transarterial treatments like embolization, chemoembolization and intraarterial chemotherapy can also be used alone or in combination with percutaneous ablation for pain palliation.