FREQUENTLY TREATED CANCER TYPES
1. LIVER CANCER
Cancer of the liver may be primary (originated from the liver cells), or secondary (metastases from the cancers of other organs). The most common primary liver tumors are hepatocellular carcinoma and cholangiocarcinoma, other primary tumors are rare. Metastases are mostly from large bowel tumors (colon cancer), but cancers of the breast, ovaries, lung, pancreas and kidney also commonly metastasize to liver.
If an abnormality is detected in the liver with ultrasound, CT or MRI, a biopsy is frequently necessary to find out its nature. In this situation, an ultrasound-guided percutaneous liver biopsy is usually preferred.
Hepatoselüler karsinom (HCC)
Hepatocellular carcinoma (HCC) makes up about 75% of all primary liver cancers. It originates from the liver cells called hepatocytes and is commonly seen in patients with chronic hepatitis B or C infection and alcoholic cirrhosis. HCC is among the five most commonly seen cancer types in the world. In most patients with HCC, a substance called alpha fetoprotein (AFP) is elevated in the blood. AFP and ultrasound are used in the screening and follow-up of high-risk patients with chronic hepatitis or cirrhosis. If there is an increase in AFP levels or a suspected nodule is seen on ultrasound, a CT or MRI is taken with intravenous contrast. In such patients, sometimes a tumor is seen on CT or MRI and a percutaneous biopsy is done for diagnosis. Sometimes the tumor has so typical features on CT or MRI that diagnosis of HCC can be reliably made without a biopsy.
HCC was one of the most fatal cancer types until a decade ago. Today, it is considered to be a curable disease if detected at an early stage. In HCC, the most commonly used staging system is BCLC (Barcelona Clinic Liver Cancer) In this classification, HCC is devided into three main stages based on the size-number of tumors, liver function and performance status of the patient.
Early HCC: Patients with less than 3 tumors, each <3cm in size with a good performance and liver function.
Intermediate-advanced stage: Patients with more or larger tumors who have a moderate performance and liver function.
Terminal stage: Patients with an impaired hepatic function, bad general status and performance, who have to spend most their lives in bed.
Early stage HCC makes up about 10-20% of the patient population. In these patients, it is possible to achieve complete cure and therefore, curative treatments are indicated. In HCC, there are 3 potentially curative treatments. These are surgical removal (resection), liver transplantation and percutaneous ablation. In the literature, there is insufficient evidence as to which of these treatments is best for the patient. However, percutaneous ablation is more and more preferred because it is a minimally invasive procedure and has less side effects. Many ablation techniques have been utilized in HCC so far, among them, radiofrequency ablation is the most frequently used one.
In the intermediate-advanced stage, there is little chance for a complete cure. However, some patients can be made suitable for curative treatments, such as ablation or operation, by decreasing the tumor size and number, or by increasing the volume of the normal liver lobe. For example, if there are too many or large HCC tumors, they can be reduced in number and size by radioembolization or chemoembolization, and then, the remaining tumors can be treated with percutaneous ablation or surgery. Or, if such tumors are located only in the right liver lobe and the left lobe is small in size, the volume of the left lobe can be increased with portal vein embolization, and when its volume becomes sufficient, the right liver lobe can be surgically removed along with the tumors. If the patient can not be made suitable for curative treatments using these methods, it is recommended to receive chemotherapy (sorafenib) or chemoembolization. It has been shown that both methods may increase survival in intermediate-advanced stage patients. There is also evidence that if these two treatments are applied concomitantly, the survival may be further increased.
In the terminal stage, none of these treatments are suitable and may be even harmful. For this reason, in such patients, the best approach is to give supportive and palliative care.
HCC is one of the cancer types where interventional radiologic treatments are used most extensively. Except for the terminal stage patients where none of the treatment options are suitable, interventional radiologic treatments can be potentially beneficial in almost all patients with HCC. The widespread application of these treatments is one of the most important factor for the better survival rates of HCC patients.
Cholangiocarcinoma originates from the bile channels and is the second commonest primary tumor of the liver. Normally, the bile channels (ducts) of the left and right lobe unite to form the main bile duct. The main bile duct then unites with the gall bladder and pancreatic ducts and opens to the small bowel. Cholangiocarcinoma may arise from anywhere along these ducts. It is named as intrahepatic cholangiocarcinoma when it originates from the small bile ducts inside the liver and as extrahepatic cholangiocarcinoma when it originates from the large bile ducts outside the liver. The most prominent clinical symptom of cholangiocarcinoma is jaundice, which is due to the obstruction of the bile channels. Jaundice is generally obvious in extrahepatic cholangiocarcinomas but may be absent in intrahepatic cholangiocarcinomas. If cholangiocarcinoma is clinically suspected, the tumor can be seen with ultrasound, CT or MRI and can be easily diagnosed with a percutaneous biopsy. However, diagnosis is generally delayed since most cholangiocarcinomas do not cause any symptoms until the late stages.
The ideal treatment of cholangiocarcinoma is surgery. However, since diagnosis is made relatively late, most patients are not suitable to surgery at the time of diagnosis. In such patients, standart therapies such as chemotherapy and/or radiotherapy are usually given. Interventional radiologic treatments can also be performed in inoperable cholangiocarcinomas besides these standart therapies. The most commonly employed interventional treatments are percutaneous ablation and radioembolization.
Thermal ablation methods such as radiofrequency, microwave and cryoablation can be successfully used in peripheal intrahepatic cholangiocarcinomas. However, they are not recommended in central or extrahepatic cholangiocarcinomas, which originate from the large bile ducts, since they may be harmful to these bile ducts. In such cases, irreversible electroporation (IRE), which is also known as nanoknife may be safe and effective, as it is considered not harmful to blood vessels and bile channels. Another potentially beneficial interventional treatment in cholangiocarcinoma is radioembolization. In fact, cholangiocarcinoma is not considered very suitable for transarterial treatments since it is not a hypervascular tumor unlike HCC. However, since the particles used in radioembolization are very small, they can diffuse into the small vessels (capillaries) of the tumor and be quite effective.
3. LIVER METASTASES:
Liver is one of the most preferred organs for metastases. The reasons for this are that liver is a relatively large organ and has a double blood supply; one from the systemic circulation via the hepatic artery, and the other, from the portal circulation via the portal vein. As a result, liver metastases are seen much more frequently (about 20 times more) than its primary tumors like HCC and cholangiocarcinoma.
Liver metastases originate mostly from the large bowel and stomach and to a lesser extent, from breast, ovaries, lung, pancreas and kidney. Metastases are generally detected with ultrasound, CT or MRI sometimes during the staging of a known tumor, or sometimes just by coincidence. Percutaneous biopsy can not only help establish the definitive diagnosis, but also give an idea about the origin of the metastasis.
In most patients with liver metastases, there may also be other metastases elsewhere (lung, bone, lymph nodes etc) in the body. For such patients, the only therapeutic option is chemotherapy and interventional treatments are generally not indicated. In some patients however, metastases are predominantly or only located in the liver. In such patients, there are many therapeutic options including various interventional treatments:
1. Surgery: If the patient is young, has a good general condition, metastases are located in only one lobe and few, then this lobe of the liver can be surgically removed (resection). In some patients, it may be necessary to enlarge the other lobe with portal vein embolization before the operation.
2. Percutaneous ablation: : If the metastases are few (less than 5) and small (less than 3cm in size) they can be treated with percutaneous ablation. Unlike surgery, percutaneous ablation can be performed in unfit patients and for tumors located in both lobes of the liver. The most frequently used ablation technique in liver is radiofrequency, although microwave and cryoablation are also used increasingly. If the metastases are in critical locations (close to the large bile ducts and blood vessels) IRE can also be used alone or in combination.
3. Combined surgery and percutaneous ablation If metastases are mostly located in one lobe (suitable for surgery) and the remaining few are located in the other lobe (suitable for ablation), then first ablation can be performed for tumors in one lobe, and then the other lobe can be surgically removed. This treatment may be possible only if the volume of the remaining liver lobe would be sufficient for the patient after percutaneous ablation and surgery.
4. Intraarterial chemotherapy: In this treatment, the chemotherapeutic drug is directly given into the liver artery instead of into a systemic vein. In this way, the drug is given to the liver metastases in a much higher concentration. For intraarterial chemotherapy, either the patient undergoes femoral angiography every 2-3 weeks and the drug is injected via a catheter, or a permanent port is implanted to the groin, which is connected to a catheter placed into the hepatic artery, and the drug is injected via this port whenever wanted.
5. Radioembolization: In this treatment, first, a radioactive material called Y90 is loaded into very small particles, and then, these particles are injected into the liver arteries via angiography. In this way, a kind of “internal radiotherapy” is done. Radioembolization is a commonly employed method in liver metastases. Generally, it is first done to one lobe of the liver, and if there is a favorable response, then it is done to the other lobe.
6. Chemoembolization: Although mostly used for hepatocellular carcinoma, chemoembolization has also a place in the treatment of metastases particularly in colon cancer metastases. In this treatment, first, special particles are loaded with a chemotherapeutic drug (for colon cancer metastases, generally irinotecan), and then, these particles are injected into the feeding arteries of liver metastases. These particles not only occlude the feeding vessels but they also excrete the loaded drug slowly into the tumor for days or weeks.
7. Chemosaturation:In this treatment, the arteries and veins of the liver are isolated from the systemic circulation, and the liver is “washed” with a very highly concentrated chemotherapeutic agent called melphalan. Melphalan is effective in many types of metastases, but it is used mostly in malignant melanoma metastases. Since the drug circulates in only the liver vessels, and the blood is filtered before given to the systemic veins, melphalan passes very little to the systemic circulation and thus, it has little or no side effects.