Secondary Liver Cancer

The initial site of a cancer in the body is referred to as the "primary" cancer. When a cancer spreads or metastasizes to another part of the body, the new site is called a "secondary"; cancer. When colorectal cancer (CRC) has metastasized to the liver, it can also be referred to as 'hepatic mCRC'. The liver is the most common site of metastasis in people with CRC; over 50% of people diagnosed with colorectal cancer will develop mCRC to the liver.19,20 This section will discuss how CRC can lead to metastasis and what happens when it spreads to the liver.

How CRC Spreads to the Liver

As the CRC tumor grows, some tumor cells may break away, spreading to other parts of the body through the blood stream or lymph vessels. As these cancerous cells spread to other tissues or organs they may begin to grow and form new, secondary tumors.4 The hepatic portal vein provides a direct blood supply between the colon and the liver; as a result, the liver is the most common site of CRC metastases.20

Regardless of the location of a secondary tumor, it is always named according to its place of origin. When CRC metastasizes to the liver, it is regarded as CRC that has spread to the liver, not as liver cancer. As such, it is treated as colorectal cancer.4

Staging of CRC

Staging is the process of determining how far the cancer has spread within the body.21,22 For CRC, the stage is based on how far the cancer has grown into the bowel wall, if it has extended to nearby structures, and if it has reached the lymph nodes or distant organs.22 Staging is important as it helps doctors decide the most appropriate treatment for each patient.21,22 One staging system used by doctors is the tumor-node-metastasis (TNM) system.21

The 'T' component can be staged as:21
  • T1: the tumor is only in the inner layer of the bowel
  • T2: the tumor has grown into the muscular layer of the bowel wall
  • T3: the tumor has grown into the outer lining of the bowel wall
  • T4: the tumor has grown through the outer lining of the bowel wall

The 'N' component can be staged as:21
  • N0: none of the lymph nodes contain cancer cells
  • N1: one, two or three of the lymph nodes close to the bowel contain cancer cells
  • N2: there are cancer cells in four or more lymph nodes

The 'M' component can be staged as:21
  • M0: no metastasis
  • M1: one or more secondary tumors have developed

There is also a number-based approach for staging tumors, from I-IV. CRC with liver metastases is stage IV.21
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Symptoms of mCRC of the Liver

If CRC has spread to the liver, a patient may experience little to no symptoms, or may notice new vague symptoms, including the following:20,23
  • Fatigue
  • Loss of appetite
  • Jaundice
  • Itchy skin
  • Dark-colored urine
  • Abdominal pain
  • Abdominal swelling/bloating
  • Fever

Testing for mCRC of the Liver

Liver metastases are often detected as part of routine tests and scans given during or following treatment for primary CRC. In some cases, the presence of metastatic cancer may be diagnosed at the same time as primary CRC.24

To test for mCRC of the liver, doctors may order any of the following tests:24
  • Computed tomography (CT), magnetic resonance imaging (MRI) or positron emission tomography (PET) scans
  • Blood tests
  • Liver biopsy