What is known as the spread and growth of cancer cells at a distance from the primary site of the cancer?

The term cancer refers to a group of diseases. Although there are over 100 different types of cancer, all cancers are characterised by abnormal cell growth. If left untreated, this disease can lead to death.

How Cancer Starts

Your body is made up of trillions of living cells. Within each cell are genes that control and direct the cell’s functions. Normal cells continuously grow and divide. Over time, they die and are replaced by new ones.

In most people, this natural cell replacement occurs in an orderly and organised manner. However, this process sometimes breaks down. Unlike normal healthy cells, cancer cells do not die. Instead, they continue to grow and divide in an uncontrollable manner. These defective cells may form a mass of tissue called a tumour.

What Are Tumours

Tumours can be benign or malignant. Tumours that stay in one location and do not spread to other parts of the body are considered to be benign. These are not cancerous and are rarely life-threatening although they can sometimes cause problems, especially when they grow too big.

On the other hand, malignant tumours can destroy and invade other normal tissues in your body, making you very sick. However, not all types of cancer form tumours. For instance, tumours are uncommon in leukaemia. These are cancers that typically start in the bone marrow and enter the bloodstream.

When Cancer Spreads

Cancer cells can spread when they migrate to other parts of the body through the blood and lymph systems, forming new tumours. This process is called metastasis. Even when cancer spreads, it is always named based on where it first occurred. For instance, cancer that begins in the breast is called breast cancer. If it spreads to other parts of the body, like the liver or bone, it is called metastatic breast cancer.

With so many different cancers, it is important for you to know which type of cancer you have so that you can receive the right treatment.

If you or a loved one is told that you have advanced cancer, it’s very important to find out exactly what the doctor means. Some may use the term to describe metastatic cancer, while others might use it in other situations. Be sure you understand what the doctor is talking about and what it means for you.

What is advanced cancer?

Advanced cancer is most often used to describe cancers that cannot be cured. This means cancers that won’t totally go away and stay away completely with treatment. However, some types of advanced cancer can be controlled over a long period of time and are thought of as an ongoing (or chronic) illness.

Even if advanced cancer can’t be cured, treatment can sometimes:

• Shrink the cancer 
• Slow its growth
• Help relieve symptoms
• Help you live longer

For some people, the cancer may already be advanced when they first learn they have the disease. For others, the cancer may not become advanced until years after it was first diagnosed.

Advanced cancers can be locally advanced or metastatic.

Locally advanced means that cancer has grown outside the body part it started in but has not yet spread to other parts of the body. For example, some cancers that start in the brain may be considered advanced because of their large size or closeness to important organs or blood vessels. This can make them life-threatening even though they haven’t spread to other parts of the body. But other locally advanced cancers, such as some prostate cancers, may be cured.

Metastatic cancers have spread from where they started to other parts of the body. Cancers that have spread are often thought of as advanced when they can’t be cured or controlled with treatment. Not all metastatic cancers are advanced cancers. Some cancers, such as testicular cancer, can spread to other parts of the body and still be very curable.

As advanced cancer grows, it can cause symptoms. These symptoms can almost always be managed with treatment, even when the cancer itself no longer responds to treatment.

What is metastatic cancer?

Metastatic cancer is a cancer that has spread from the part of the body where it started (the primary site) to other parts of the body. When cancer cells break away from a tumor, they can travel to other parts of the body through the bloodstream or the lymph system. (Lymph vessels are much like blood vessels, except they carry a clear fluid and immune system cells.)

This image shows some parts of the lymph system, like lymph nodes and lymph vessels, as well as organs and tissues that contain many lymphocytes (immune cells).

If the cells travel through the lymph system, they could end up in nearby lymph nodes (small, bean-sized collections of immune cells) or they could spread to other organs. More often, cancer cells that break off from the main tumor travel through the bloodstream. Once in the blood, they can go to any part of the body. Many of these cells die, but some may settle in a new area and start to grow. 

Cancer cells must go through several steps to spread to new parts of the body:

• They must find ways to break away from the original tumor and enter the bloodstream or lymph system.
• They need to attach to the wall of a blood or lymph vessel and move into a new body part.
• They need to find ways to grow and thrive in their new location.
• They must be able to avoid attacks from the body’s immune system.

When cancer spreads to a new area, it’s still named after the part of the body where it started. For instance, breast cancer that has spread to the lungs is called “metastatic breast cancer to the lungs” – it’s not lung cancer. Treatment is also based on where the cancer started. If prostate cancer spreads to the bones, it’s still prostate cancer (not bone cancer), and the doctor will choose treatments that have been shown to help against metastatic prostate cancer. Likewise, colon cancer that has spread to the liver is treated as metastatic colon cancer, not liver cancer.

Sometimes the metastatic tumors have already begun to grow when the cancer is first found. And sometimes, a metastasis may be found before the original (primary) tumor is found. If a cancer has already spread to other parts of the body before it’s first diagnosed, it may be hard to figure out where it started.

Why cancer cells tend to spread to the parts of the body they do

Where a cancer starts is linked to where it will spread. Most cancer cells that break free from the primary tumor are carried in the blood or lymph system until they get trapped in the next “downstream” organ or set of lymph nodes. This explains why breast cancer often spreads to underarm lymph nodes, but rarely to lymph nodes in the belly. Likewise, there are many cancers that commonly spread to the lungs. This is because the heart pumps blood from the rest of the body through the lungs’ blood vessels before sending it elsewhere.

Possible symptoms of advanced and metastatic cancer

General signs and symptoms of advanced and metastatic cancer can include:

• Loss of energy and feeling tired and/or weak: This can get so bad that you may have a hard time doing everyday tasks like bathing or getting dressed. People with advanced cancer often need help with these things.
• Weight loss (without trying)
• Pain
• Shortness of breath or trouble breathing

Advanced and metastatic cancers can cause many other symptoms, depending on the type of cancer and where it has spread.

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