Understanding Metastatic Disease Cancer

A cancer diagnosis often begins with a small but worrying sign, such as a lump that was noticed, a scan that shows something unusual, or a pain that does not fade. In the early moments, it can seem like the problem exists in just one place. The focus naturally stays on that single spot.

But cancer does not always remain limited to where it first begins. In some cases, certain cancer cells break away and travel through the body, eventually settling in other organs and starting to grow there. When this happens, the disease is known as metastatic cancer, and it still carries the name of the place where it originally started.

Understanding this process is an important step in understanding the disease itself. In this blog, we will explore how cancer moves through the body, what factors can lead to this spread, and how modern medicine works to manage metastatic disease.

What is Metastasis?

Metastasis is the medical term used to describe how cancer spreads from its original location to other parts of the body. When cancer remains confined to the place where it first develops, it is considered a local disease. But when cancer cells begin to spread and grow in other organs, the illness becomes systemic, meaning it affects multiple parts of the body rather than staying limited to one area.

From a biological perspective, metastasis is a complex and challenging process for cancer cells. Many of the cells that break away from the primary tumour fail to survive while travelling through the bloodstream or lymphatic system and facing the body’s immune defences. Only a few manage to reach another organ and find the right conditions to grow. When cancer spreads in this way to distant organs, doctors classify it as Stage IV cancer.

How Cancer Spreads?

Cancer does not spread randomly. It follows a series of biological steps that allow cancer cells to move through the body, often using the bloodstream and lymphatic system as pathways.

• Local Invasion: The process begins when cancer cells start growing into the healthy tissues surrounding the original tumour.
• Intravasation: Some cancer cells break through the walls of nearby blood vessels or lymph vessels, allowing them to enter these systems.
• Circulation: Once inside the bloodstream or lymphatic system, the cancer cells travel to different parts of the body.
• Arrest and Extravasation: The cells may stop in small blood vessels called capillaries and then pass through the vessel walls into nearby tissue.
• Colonisation: In the new location, cancer cells begin to multiply and form small tumours known as micrometastases.
• Angiogenesis: To keep growing, the tumour signals the body to create new blood vessels so it can receive oxygen and nutrients.

Which Cancers can Metastasise?

Not all cancers spread in the same way. While almost any type of cancer can become metastatic, some cancers are more likely to spread than others. This often depends on how aggressive the tumour is and how early the cancer is detected and treated.

• Breast cancer: Often spreads to the bones, lungs, liver, and brain.
• Colorectal cancer: Most commonly migrates to the liver and lungs.
• Oesophageal cancer: Frequently moves to the liver, lungs, and lymph nodes.
• Lung cancer: Can spread to the adrenal glands, liver, bones, and the other lung.
• Ovarian cancer: Usually stays within the abdominal cavity, affecting the peritoneum and liver surface.
• Pancreatic cancer: Known for spreading quickly to the liver and lungs.
• Prostate cancer: Has a strong affinity for the bones.
• Skin cancers (Melanoma): Can travel almost anywhere, including the brain, lungs, and liver.
• Stomach cancer: Often affects the liver and the lining of the abdomen.
• Uterine cancer: May spread to the bladder, rectum, or distant organs like the lungs.

Where does Cancer Metastasise First?

The place where cancer spreads during metastasis often depends on how blood and lymph fluid move through the body. Since these systems act like transport routes, cancer cells can travel along them and settle in certain organs more commonly than others, these organs include:

• Adrenal glands
• Bones
• Brain
• Liver
• Lungs
• Peritoneum

What are the Symptoms of Metastatic Disease?

In advanced stages, cancer symptoms are often not caused by the original tumour but by the organs where the cancer has spread (metastasis). The signs usually reflect how the affected organ is functioning.

• Bone pain and fractures: If cancer has spread to the skeletal system, it can weaken bones and cause intense localised pain.
• Shortness of breath: When tumours grow in the lungs, they interfere with oxygen exchange, leading to shortness of breath or a persistent cough.
• Headaches and seizures: These are common indicators that cancer may have reached the brain, affecting neurological function causing severe headache and seizures.
• Jaundice: A yellowing of the skin and eyes often indicates that the liver is struggling due to tumour growth.
• Abdominal swelling (Ascites): This occurs when cancer spreads to the peritoneum, causing fluid to build up in the belly.
• Unexplained weight loss and fatigue: A systemic symptom as the body’s metabolism is hijacked by the growing tumours.

What Causes Metastasis?

Scientists are still trying to fully understand why some cancer cells leave the original tumour and spread to other parts of the body. However, research has identified several biological factors that may trigger this process.

A Weakened Immune System

Normally, the immune system helps detect and destroy abnormal cells. But if the immune system becomes weak, or if cancer cells manage to hide from it, those cells may survive and travel to other parts of the body.

Hypoxia 

As a tumour grows larger, the centre of the tumour may not get enough oxygen. This lack of oxygen can push cancer cells to move away and search for areas with better oxygen supply.

Lactic Acidosis

Cancer cells produce energy in a different way than normal cells, which leads to a build-up of lactic acid. This creates an acidic environment that weakens the surrounding tissue, making it easier for cancer cells to break away and spread.

Autophagy

Autophagy is usually a process where cells break down parts of themselves to survive stress. Cancer cells can use this process to survive while travelling through the body and adapting to new environments.

How is Metastatic Disease Diagnosed?

When doctors suspect that cancer may have spread beyond its original location, they perform several tests to understand how far the disease has progressed.

Imaging Tests

• CT scans create detailed cross-sectional images of the body.
• MRI scans are especially helpful for examining the brain and spinal cord.
• PET scans use a small amount of radioactive tracer to highlight areas of high activity in the body, which may indicate the presence of cancer.

Biopsy

If a scan shows a suspicious growth in another part of the body, doctors may perform a biopsy. This involves removing a small sample of tissue to confirm whether the new growth is cancer and to check if the cancer cells have changed genetically.

Blood Tests and Tumour Markers

Some cancers release specific proteins, known as tumour markers, into the bloodstream. Measuring these markers through blood tests helps doctors track whether the cancer is spreading and assess how well the current treatment is working.

What is The Treatment for Metastatic Disease?

In the past, advanced cancer was often considered untreatable. Today, many treatments aim to control the disease, slow its growth, shrink tumours, and help patients maintain a good quality of life.

Chemotherapy

Chemotherapy uses powerful drugs that travel through the bloodstream to destroy cancer cells. Because the drugs circulate throughout the body, they can reach cancer cells that have spread to different organs.

Hormone Therapy

Some cancers, such as certain breast and prostate cancers, grow with the help of hormones. Hormone therapy works by blocking these hormones or lowering their levels, which helps slow or stop the cancer’s growth.

Immunotherapy

Immunotherapy helps the body’s own immune system fight cancer. These medicines help the immune system recognise cancer cells and attack them more effectively.

Radiation Therapy

Radiation therapy uses high-energy rays to shrink tumours. In metastatic cancer, it is often used to reduce pain or relieve pressure on important parts of the body, such as the spine or airways.

Targeted Therapy

Targeted therapy focuses on specific genes or proteins that help cancer grow. By attacking these particular weaknesses in cancer cells, these treatments can slow the disease while causing fewer side effects than some traditional treatments.

What are the Survival Rates of Metastatic Cancer?

Survival rates for metastatic disease can vary a lot depending on the type of cancer and how well it responds to treatment. It is also important to remember that survival statistics are based on large groups of people, so they cannot accurately predict what will happen for an individual patient.

According to data from the SEER database and Cancer Research UK, the five-year relative survival rate for metastatic breast cancer is around 28–30%, while for metastatic prostate cancer it is about 30%.

In some cancers, outcomes have improved significantly because of newer treatments. For example, advances in immunotherapy have greatly improved survival rates for melanoma over the past decade. Today, many patients are able to live for several years with metastatic cancer as treatments continue to improve and new options become available.

Living with metastatic cancer

Living with an advanced cancer diagnosis often requires a different perspective. Instead of focusing only on a cure, the goal becomes living as well as possible and maintaining quality of life.

Palliative Care

Palliative care focuses on relieving symptoms such as pain, fatigue, or discomfort. It aims to improve comfort and quality of life alongside ongoing cancer treatment.

Emotional Support

Living with regular scans and uncertainty can be stressful. Support groups, counselling, and talking with loved ones can help manage anxiety and emotional challenges.

Physical Activity

Light or gentle exercise can help reduce fatigue, improve mood, and support overall well-being during treatment.

Nutritional Support

A balanced diet helps keep the body strong and better able to handle treatments and recover more effectively.

Wrapping Up

Metastatic disease occurs when cancer cells spread from their original location to other parts of the body. While this stage of the disease can be more complex to manage, understanding how metastasis happens helps patients and families better understand the condition and the treatment options available. Early detection, regular monitoring, and proper medical care play an important role in managing the disease effectively.

Although metastatic cancer is challenging, advances in modern medicine have improved treatment options and patient outcomes. Many therapies today focus on slowing the disease, reducing symptoms, and helping patients maintain a better quality of life. With the right treatment, supportive care, and emotional support, many people are able to continue living meaningful and fulfilling lives while managing the disease.

FAQs

1. Can cancer metastasise years after the original tumour was treated?

Yes. In some cases, a few cancer cells may remain inactive in the body for many years. These cells can later become active again and start growing, leading to metastatic cancer.

2. What is Cancer of Unknown Primary (CUP)?

Cancer of Unknown Primary happens when doctors find metastatic tumours in the body but cannot identify where the cancer originally started, even after several tests and scans.

3. What is the difference between metastatic recurrence and a second primary cancer?

Metastatic recurrence means the original cancer has spread to another part of the body. A second primary cancer is a completely new and unrelated cancer that develops separately.

4. Can benign (non-cancerous) tumours metastasise?

No. Benign tumours can grow larger and press on nearby tissues, but they do not spread to other organs like cancer cells do.

5. How fast can cancer spread to other organs?

The speed of metastasis depends on the type of cancer and how aggressive it is. Some cancers spread within months, while others may take many years or may never spread.