Management of liver metastases from colorectal cancer
Which are the symptoms?
In many cases, liver metastases remain asymptomatic for a long time and cannot be detected by simple palpation until they reach a significant size. However, over time, the presence of metastases can disrupt liver function and cause symptoms such as subfebrile fever, a feeling of heaviness in the upper abdomen, pain in the right side, fatigue, loss of weight and appetite, nausea, jaundice, confusion, etc. Currently, there are no effective preventive measures (other than chemotherapy) to prevent the tumor from metastasizing to the liver. Therefore, the best prevention is the early detection of primary cancer and regular check-ups for timely detection of relapses. Moreover, since liver metastases can develop months or years after the primary tumor is diagnosed, liver tests are common for many types of cancer (primarily colorectal cancer) even after treatment is discontinued.
How is it diagnosed?
In the case of signs and symptoms that may indicate liver metastases (previous cancer with a tendency to liver metastases, weight and appetite loss, nausea, abdominal pain, jaundice), the doctor will prescribe blood tests to assess liver function and the level of certain cancer markers, such as CEA and CA-19-9, which increase, for instance, in the case of colorectal metastases, even after the removal of the primary tumor. However, to better characterize any liver metastases, diagnostic imaging studies are needed: ultrasound, magnetic resonance imaging, computed tomography (CT), positron emission tomography (PET), which make it possible to understand exactly the number of metastases, how extensive they are and where they are located. A biopsy, i.e., taking liver tissue cells to be analyzed under a microscope, is performed only if there are still doubts after the above tests.
How is it treated?
As mentioned earlier, surgery is the most optimal solution and the only method of treatment (the gold standard of treatment). The possibility of surgical intervention significantly depends on the coexistence of two conditions: the complete elimination of the disease and the preservation of a sufficient amount of the liver to maintain vital activity in the postoperative period. In fact, it should be remembered that the liver has the ability to recover, returning to its original size and function after surgery, but this process takes several months. The risk of liver failure after surgical resection is considered low if at least 40% of the liver is preserved, moderate for residual liver amounts from 40% to 25%, high for volumes less than 25%. In cases where the two conditions mentioned above do not co-exist, surgical excision may be reviewed by applying certain strategies to reduce the volume of metastases before surgery (neoadjuvant chemotherapy) or to increase the volume of the liver to be preserved (preoperative portoembolization). It is also possible to schedule the removal of all metastases with two operations 1-2 months apart (“two-step hepatectomy”) to allow the liver to regenerate between the first operation and the next one, or after a shorter period of time using a new procedure suitable in very select cases called ALPPS (Associating Liver Partitioning and Portal Vein Ligation for Staged Hepatectomy).
As a rule, the operation consists in removing the tumor focus and the surrounding part of the liver so that at least 1 cm of healthy tissue remains between the edge of the tumor and the liver cross-section line, although in certain conditions it is permissible to leave a less thick edge of healthy tissue if this makes it possible to completely remove the tumor while maintaining a sufficient amount of liver.
In patients with liver metastases that are synchronous with colorectal cancer (that is, when metastases are diagnosed simultaneously with primary cancer, during interim tests), the nodules can be removed during colon cancer surgery: thus, the patient undergoes only one operation and is hospitalized once. In addition, in some cases of synchronous metastases, in which it is impossible to intervene directly on both fronts and where the degree of liver disease can significantly affect the patient’s prognosis, liver metastases can be removed before the primary tumor is removed (the “liver first” technique).
Although traditional surgical resection is recommended for patients with metastases exclusively in the liver, recent studies offer promising predictions in the near future for patients with metastases in the liver and extrahepatic abdominal areas (lymph nodes, peritoneum, adrenal glands) or extraabdominal (lungs), provided that all areas of the tumor are removed during the operation.
However, the percentage of patients amenable to surgical treatment at the time of diagnosis is not more than 20-30% of cases; the number of metastases and / or their location in the liver (infiltration of large blood vessels) and / or the degree of replacement of a healthy liver with a tumor often exclude the possibility of surgical resection. In these cases, the appropriate treatment is chemotherapy.
The recent development of more effective chemotherapeutic medicines, such as oxaliplatin and irinotecan, has made it possible to achieve important results in the field of oncology, and in fact has led to a significant reduction in tumor mass and an increase in the survival rate in patients with inoperable metastases, and thus has led to the appearance of 10-20% of initially inoperable patients in addition to those already suitable for surgery.
Systematic chemotherapy is often offered to patients with metastatic colorectal cancer (including candidates for surgery, with some exceptions), before (neoadjuvant chemotherapy) and / or after (adjuvant chemotherapy) liver surgery precisely because it makes it possible to consolidate the long-term results of the operation.
Drugs are usually injected into a vein (intravenously) for distribution throughout the body (systemic chemotherapy). However, if metastases are found only in liver, the possibility of administration directly to the liver (regional chemotherapy) through an arterial blood vessel (intra-arterial chemotherapy) may also be considered. In fact, this method can be used to inject drugs into the liver that are very effective in metastases and that, although highly toxic to the body, are administered in very high doses without much side effects, since the medication is destroyed by the liver itself before it spreads throughout the body.