Cancer Metastases to Liver

What is Colorectal Liver Metastases (CRLM)?

Colorectal liver metastases (CRLM) occur when cancer cells from the colon or rectum spread to the liver. This happens through the portal venous system, a network of veins that drains blood from the intestines and transports it to the liver. Because of this direct connection, the liver is the most common site of metastasis in colorectal cancer.

Liver metastases are not considered a different type of cancer; rather, they are colorectal cancer cells that have implanted and grown in the liver. Pathologically and biologically, they retain the characteristics of the original colorectal tumour, which is why treatment decisions are often based on the behaviour of the primary colorectal cancer.

CRLM may be detected at the time of initial diagnosis of colorectal cancer (known as synchronous metastases) or may appear months or years later (metachronous metastases). Studies estimate that approximately 50% of patients diagnosed with colorectal cancer will develop liver metastases during the course of their disease.

The presence of liver metastases marks a more advanced stage of cancer, but it does not automatically preclude treatment. In selected cases, especially when the disease is limited to the liver, curative treatment is possible. Advances in surgical techniques, systemic therapies (such as chemotherapy and targeted therapy), and liver-directed treatments (like ablation or embolisation) have significantly improved survival rates for patients with CRLM. With appropriate management, long-term survival, and in some cases, complete remission is achievable.

What causes Colorectal Liver Metastases (CRLM)? 

Colorectal liver metastases (CRLM) are caused by the spread of cancer cells from a primary tumour in the colon or rectum to the liver. This process, known as metastasis, occurs through a complex series of steps that allow malignant cells to detach from the original tumour, enter the bloodstream, and implant in distant organs, most commonly, the liver.

The role of the portal venous system

The liver is the most frequent site of metastasis in colorectal cancer due to its unique blood supply. Blood from the colon and rectum drains directly into the liver through the portal vein. When colorectal cancer cells invade blood vessels near the tumour, they can enter this venous system and travel to the liver. Once in the liver, these circulating tumour cells may settle, survive, and form new metastatic growths.

Tumour biology and aggressiveness

Not all colorectal cancers metastasise to the liver. Certain biological characteristics influence the likelihood of liver spread, including:

• Tumour stage and depth of invasion — cancers that penetrate deeper into the bowel wall or nearby lymph nodes are more likely to metastasise.

• Histological grade — poorly differentiated tumours tend to behave more aggressively.

• Genetic mutations — alterations in genes such as KRAS, NRAS, BRAF, and TP53 are associated with a higher risk of metastatic spread and may also influence response to treatment.

• Lymphovascular invasion — when cancer cells are found in blood vessels or lymphatics near the tumour, the risk of metastasis is significantly increased.

CRLM may be present at the time of initial colorectal cancer diagnosis (synchronous) or may appear later during follow-up (metachronous). Synchronous metastases suggest early dissemination of tumour cells, whereas metachronous disease may reflect tumour evolution and adaptation over time.

What are the symptoms of Colorectal Liver Metastases (CRLM)?

Colorectal liver metastases (CRLM) often develop silently, without obvious symptoms in the early stages. Many cases are identified during routine scans performed for colorectal cancer follow-up or staging. When symptoms do appear, they may reflect the growing impact of liver involvement or general signs of cancer progression.

• Right upper abdominal discomfort or pain — may be dull, persistent, and caused by stretching of the liver capsule as tumours grow.

• Fatigue and unexplained weight loss — can result from the body’s increased energy demands due to cancer and reduced nutritional intake.

• Loss of appetite — patients may experience early satiety, nausea, or general disinterest in food.

• Enlarged liver (hepatomegaly) — the liver may feel enlarged or firm during physical examination as metastatic lesions grow.

• Jaundice — yellowing of the skin or eyes may occur if bile ducts become blocked by tumours, indicating more extensive liver involvement.

• Abdominal swelling (ascites) — fluid buildup in the abdomen may develop when liver function is impaired or portal pressure rises.

• Fever or malaise — non-specific symptoms like low-grade fever or a general sense of unwellness may occur due to tumour-related inflammation.

It’s important to note that many patients with CRLM have no symptoms at all, especially in the early stages. This is why regular follow-up and surveillance imaging (such as CT scans or MRIs) after colorectal cancer treatment are crucial for timely detection. In fact, the earlier CRLM is diagnosed, especially before the symptoms appear, the better the chances for effective treatment, including potential surgical resection.

Who is at risk of Colorectal Liver Metastases (CRLM) in Singapore?

In Singapore, colorectal cancer remains one of the most commonly diagnosed cancers, particularly among men. As the liver is the most frequent site for metastatic spread, understanding who is at higher risk of developing colorectal liver metastases (CRLM) is important for early detection and timely intervention.

• Patients with advanced colorectal cancer — individuals diagnosed at stage III or IV have a significantly higher likelihood of liver metastases due to regional lymph node involvement or distant spread.

• Presence of lymphovascular invasion — when cancer cells are found in nearby blood vessels or lymphatics, the chances of those cells travelling to the liver are increased.

• Aggressive tumour biology — patients with poorly differentiated tumours or adverse genetic profiles (e.g. KRAS, NRAS, BRAF mutations) tend to have a higher risk of metastasis.

• Rectal or sigmoid colon tumours — tumours located in the lower sections of the large intestine have a stronger association with liver metastases, partly due to patterns of venous drainage.

• Delayed or incomplete treatment — individuals who experience delays in diagnosis or treatment, or who receive suboptimal surgical resection, may face a higher risk of recurrence and metastatic spread.

• Family history and lifestyle factors — although not direct causes of metastases, family history of colorectal cancer, smoking, low-fibre diets, obesity, and physical inactivity contribute to more aggressive cancer development and late-stage presentation.

• Male gender and older age — local cancer statistics show that older men in Singapore are disproportionately affected by colorectal cancer and its complications, including liver metastases.

• Recurrent colorectal cancer — patients previously treated for colorectal cancer who develop recurrence are at higher risk of the disease spreading to the liver, especially if follow-up surveillance is missed.

Early-stage colorectal cancers, if detected and treated promptly, have a much lower chance of progressing to liver metastases. This is why targeted screening and genetic profiling are increasingly integrated into treatment planning in major centres across the country.

How are Colorectal Liver Metastases (CRLM) diagnosed? 

At Tan Siong San Surgery, we combine clinical expertise with imaging tools to accurately diagnose colorectal liver metastases (CRLM), even in its early stages. 

Here are the key diagnostic methods we use:

• Blood tests and tumour markers — our doctors check for elevated levels of carcinoembryonic antigen (CEA), a protein that may be raised in colorectal cancer with liver involvement.

• Contrast-enhanced CT scan — a high-resolution scan of the chest, abdomen, and pelvis helps detect the size, number, and location of liver lesions, as well as potential spread to other organs.

• MRI of the liver — when more detailed imaging is needed, we may recommend a liver-specific MRI to better define tumour margins, particularly for smaller or surgically challenging lesions.

• PET-CT scan — this scan may be used to assess the full extent of disease, including areas that may not be visible on other scans, and to guide treatment planning.

• Colonoscopy — if the primary colorectal cancer hasn’t been confirmed yet, a colonoscopy is essential to identify and biopsy the original tumour.

• Liver biopsy — in selected cases where the diagnosis remains uncertain, we may perform a minimally invasive liver biopsy to confirm the nature of the lesion before proceeding with treatment.

What are the treatment options for Colorectal Liver Metastases (CRLM) in Singapore? 

Here are the main treatment options we offer or coordinate for patients with CRLM:

• Liver resection (surgery to remove liver metastases) — this is the only option to offer  a chance of cure. At Tan Siong San Surgery, we perform liver resections using both open and minimally invasive techniques, depending on the number, size, and location of the lesions. For selected patients, surgery offers optimal chances of long-term survival and, in some cases, complete remission.

• Ablation therapies (e.g. radiofrequency or microwave ablation) — for patients who are not suitable for surgery due to medical conditions or tumour location, local ablation is a safe and effective alternative. It uses heat energy to destroy cancerous tissue and can be performed percutaneously or in combination with surgical resection of multiple metastases.

• Systemic chemotherapy — chemotherapy is often used before surgery (neoadjuvant) to shrink tumours or after surgery (adjuvant) to reduce the risk of recurrence. It is also used for patients with widespread disease. We work closely with medical oncologists to tailor the most suitable drug regimen for each patient.

• Targeted therapy and immunotherapy — depending on your tumour’s genetic profile (e.g. KRAS, NRAS, or BRAF mutation status), you may benefit from targeted drugs that block cancer growth or boost your immune system’s ability to fight the disease.

• Liver-directed therapies (e.g. TACE or SIRT) — transarterial chemoembolisation (TACE) or selective internal radiation therapy (SIRT) may be considered in specialised cases, especially for patients with unresectable but liver-limited disease.

• Two-stage liver surgery or portal vein embolisation — for patients with extensive but potentially curable disease, we may recommend advanced surgical strategies to increase the volume of the remaining liver before proceeding with full tumour removal.

• Palliative care and symptom control — if curative treatment is not possible, we focus on controlling symptoms, slowing cancer progression, and improving quality of life through supportive care and symptom management.

Summary 

Colorectal liver metastases (CRLM) occur when colorectal cancer spreads to the liver — most commonly in stage 4 of the disease. At Tan Siong San Surgery, we provide detailed evaluation and treatment tailored to each patient’s condition, using comprehensive imaging, precise surgical techniques, and close multidisciplinary collaboration. While many patients may not experience symptoms in the early stages, timely diagnosis and intervention can significantly improve outcomes.

If you have been diagnosed with colorectal cancer or suspect liver involvement, schedule a consultation with us for a thorough evaluation and personalised treatment plan tailored to your condition.