Stage IV colorectal cancer may be initially diagnosed when the colon tumor is discovered or much later, if the colon cancer recurs in the liver. Despite early diagnosis and treatment, cancers involving the colon or rectum (colorectal cancer) can reappear at a later time, even if the cancer was entirely removed during the initial treatment. This reappearance of the cancer is called recurrence or relapse. A colorectal cancer recurrence can be either local (confined to the large intestine or nearby tissues) or at a distant site. When the recurrence develops at a site away from the colon or rectum it is called a metastasis. Although most patients with metastatic colorectal cancer develop a recurrence months to years after initial treatment, a small percentage have metastatic cancer when their tumor is first discovered.
The liver is the most common site for metastatic colorectal cancer. The treatment of patients with metastatic colorectal cancer depends upon the extent and location of the tumor involvement. Cure is not possible for most patients in this situation, although some patients who have limited involvement can be cured with surgery. For others, chemotherapy and/or regional treatment approaches may be considered as the most appropriate options. These options do not cure metastatic colorectal cancer, but may improve symptoms and prolong life.
There are several regional treatment options for patients with liver-isolated colorectal cancer metastases who are not candidates for potentially curative resection. Among them are transcatheter arterial chemoembolization and selective internal radiation using yttrium-labeled glass microspheres. The choice of regional treatment of metastatic colorectal cancer depends on the size and location of the tumor, whether the cancer has spread, and the patient’s overall health. In many cases, a team of doctors will work with the patient to determine the best treatment plan.
Liver resections are surgical procedures carried out under general anesthesia and may take anywhere from 2-5 hours to complete. The incision is usually made on the right side, below the edge of the rib cage. Most patients do not require blood transfusions. Patients are typically hospitalized for 4-6 days.
Unfortunately, not all patients are eligible for liver resection. Resection is not indicated when: 1) the tumor has spread to other parts of the liver or the body, 2) the size or location of the tumor (near major blood vessels) precludes it from being safely removed without compromising function of the remainder of the liver, 3) the associated cirrhosis or disease limits the ability to safely operate upon or remove part of the liver, and 4) other medical conditions make surgery unsafe.
A variety of liver resections can be performed. These include resection of an entire lobe (right or left), more than one lobe (extended lobectomy), or segmental resection (part of a lobe). These resections are based on the eight anatomical segments of the liver (Figure 1 & 2).
|Figure 1: Anatomical segments of the liver; A, anterior surface; B, posterior surface. |
Resection contraindications include evidence of clinical jaundice in the absence of biliary obstruction, ascites , renal insufficiency, or prolonged prothrombin or partial thromboplastin thrombosis times. The operative mortality is less than 3% for noncirrhotic patients compared with 5Ð25% for cirrhotic patients, and noncirrhotic patients are resectable in up to 60% of cases. Although most patients with cirrhosis are unresectable, those with ChildÕs A or mild cirrhosis have significantly better outcomes after liver resection than patients with more severe ChildÕs B or C cirrhosis. Although the resectability rate is low and operative mortality higher compared to liver resection for metastatic liver cancer, the 5-year survival rate after resection for hepatocellular carcinoma ranges from 25Ð65%. Favorable prognostic factors include 1) well-differentiated or fibrolamellar history, 2) absence of vascular invasion, 3) tumors less than 5 cm in diameter.
Operative morbidity and mortality from liver resection has significantly improved in recent decades, principally because of a clearer understanding of anatomic considerations, newer surgical techniques, and improved postoperative care. A variety of types of surgical resections can be performed depending on the extent and location of disease (Figure 2).
|Figure 2. Liver resections; A: right hepatic lobectomy; B: left hepatic lobectomy; C: extended left hepatic lobectomy (left trisegmentectomy, left trisectorectomy); D: extended right hepatic lobectomy (right trisegmentectomy, left trisectorectomy); E: hepatic segmentectomy; F: non- anatomical wedge resection. (Click on the blue letters to view the consecutive images) |
Minor hepatic resections include both nonanatomic wedge resections of peripheral lesions and anatomic resection of hepatic segments. Major resections include hepatic lobectomy and extended lobectomy. When performing major hepatic resection, the vascular structures supplying the liver being removed are typically isolated extrahepatically prior to parenchymal dissection. Inflow occlusion at the porta hepatis can be useful in reducing bleeding during parenchymal parenteral dissection. The noncirrhotic liver can tolerate occlusion times beyond 60 minutes without irreversible damage. However, such warm ischemia is not tolerated as well in cirrhotic livers. In such cases, total inflow occlusion should be only be used intermittently and for brief periods of time. Total vascular isolation can also be used, incorporating both inflow occlusion and control of the intrahepatic and suprahepatic vena cava. This technique, however, is associated with significant hemodynamic instability and should be used only selectively in complex cases.
Excessive blood loss during liver resection not only increases the need for blood transfusion, with its associated problems, but increases the risk of structural injury and suboptimal tumor margin clearance by obscuring the surgical field. Newer surgical techniques of vascular isolation, as well as the use of intraoperative ultrasonography, have significantly reduced the need for blood transfusions and blood products in modern liver surgery. The current literature reports that fewer than half of patients undergoing major liver resection require blood transfusions. Other techniques can be used to further reduce the need for allogenic blood transfusion.
Radiofrequency ablation (RFA) is a new technique that makes use of a “heating” probe to destroy tumors within the liver. A thin probe is placed within the tumor, typically under ultrasound guidance. After deploying the tip array, an electrical current is applied, generating heat (80–100°C) that destroys the tumor (Figure 15). RFA is generally indicated for small tumors within the liver and can be applied with minimal side effects. The advantage of this technique is that it can be used either in the operating room with an open or laparoscopic approach, or directly through the skin (percutaneous approach). As with cryotherapy, RFA can be used in conjunction with liver resection. Some of the tumor may be surgically removed, while remaining disease is treated with RFA.
|Figure 3. Radiofrequency ablation (RFA)for colorectal metastases |
Radio frequency ablation can also be performed percutaneously, causing local tissue destruction by frictional heat. When the temperature surpasses 90°C, an immediate destructive effect occurs within the tumor. This technique was first described in 1993 and is one of the most recent additions to the armamentarium against liver tumors.
|Figure 4. Percutaneous radio frequency ablation|
This procedure is also performed under ultrasound guidance. A radiofrequency needle is inserted deep into the lesion and multiple electrodes are deployed. The generator is then activated to achieve high temperatures within the tumor. The duration of the treatment varies from 6–15 minutes.
Only limited data are available regarding use of this technique to treat unresectable liver tumors, but preliminary studies have shown a trend toward prolonged survival.
Interventional Radiology Treatment Options at Johns Hopkins
Transcatheter arterial chemoembolization
Transcatheter arterial chemoembolization is a procedure where chemotherapy is injected locally inside the artery feeding the tumor, followed by short-time blockage of the tumor feeding artery, so as the anticancer drugs stay longer inside the tumor and with little damage to surrounding healthy tissues. Specifically, the interventional radiologists insert a tiny tube (catheter) inside the femoral artery at the groin and under fluoroscopic guidance drive the catheter to the artery supplying the tumor and as close to the tumor as possible (selective chemoembolization). After confirming appropriate catheter positioning, chemotherapy is injected followed by embolic beads that temporarily block the blood supply to the tumor.
Chemoembolization usually involves a hospital stay of one to two days. Patients typically have lower than normal energy levels for about a month afterwards. Some patients may experience side effects called post-embolization syndrome, including pain, nausea, vomiting and fever. These can readily be controlled by medications given by mouth and may resolve within fifteen days after treatment.
|A, B, Hepatic artery chemoembolization; A’, with corresponding angiogram. |
Radioembolization for metastatic colorectal cancer involves placing radioactive beads into the artery that supplies the tumor with blood in a manner similar to chemoembolization (see above). The radioactive isotope Yttrium-90 is incorporated into the beads to deliver radiation directly to the tumor. Like with chemoembolization, these beads are injected through a catheter from the groin into the hepatic artery supplying the tumor. The beads block the tumor vessels where they exert their local radiation that causes cell death. This technique allows for a higher, local dose of radiation to be used, without subjecting healthy tissue in the body to the radiation. The Yttrium-90 radiates from within and, since it is administered in the hepatic artery, it is considered a selective internal radiation treatment.
The general side effects from radiation therapy may include fatigue, mild skin reactions, upset stomach, and loose bowel movements. Most side effects go away soon after treatment is finished. For internal radiation therapy, there may be such side effects as damage to the stomach and lungs. However, these can often be avoided by special pre-treatment preventive measures.
Y-90Radioembolization for colorectal liver metastases
|A. Before Treatment|
|B. After Treatment|