Where a cancer spreads

Cancers can really spread just about anywhere. But most cancers tend to spread most often to one or two places in the body. There is more about how cancers spread in this section of CancerHelp UK.

The treatment for cancer that has spread (secondary cancer) depends on where the cancer started in the body (the primary cancer). So breast cancer that has spread to the lungs will be treated like a breast cancer, not like lung cancer. Where particular treatments are used for cancer that has spread, they are mentioned below.

The lungs are the most common organ for cancers to spread to. This is because the blood from most parts of the body flows back to the heart and then to the lungs before it goes to any other organ. Cancer cells that have found their way into the bloodstream can get stuck in the tiny capillaries of the lungs.

Cancer that has spread to the lungs may not cause any symptoms or may cause

• A cough that doesn't go away
• Shortness of breath
• Chest infections
• A build up of fluid between the chest wall and the lung called a pleural effusion - this in turn causes shortness of breath, chest aching, discomfort and heaviness

Fluid builds up because cancer cells are irritating the pleura (also called the pleural membrane). The pleura are the two sheets of tissue that cover the lungs. The irritated tissues make extra fluid and the fluid collects between them. There may also be cancer cells in the pleural space that stop the extra fluid draining away. The lungs inflate as we breathe in. This fluid build up gets in their way and stops them from inflating fully.

Doctors can drain the fluid away by putting in a needle, or a thin tube. This is called a pleural tap, or aspiration. But unless they can stop the fluid from collecting, it will build up again. There is detailed information about treatment for pleural effusion in our question and answer about treatment for fluid on the lung.

Many types of cancer can spread to the liver. It is most likely to occur with cancers of the digestive system because the blood from the digestive system circulates through the liver before it goes back to the heart. The cancer cells get stuck in tiny capillaries of the liver. 

Cancer that has spread to the liver can cause the following symptoms.

• A lack of energy
• Feeling generally unwell
• Feeling sick
• Lack of appetite
• Discomfort on the right side of the body under the rib cage
• Jaundice
• A build up of fluid in the abdomen (ascites)

Jaundice is the medical name for a build up of bile salts in the blood. This usually happens when the bile ducts in the liver are blocked. The build up of bile salts makes the skin and whites of the eyes turn yellow. It can also make the skin become itchy. The urine often looks very dark and bowel motions can look pale.

Ascites can happen for a number of reasons. It most often happens when cancer has spread to the liver. But it can also occur if cancer cells have spread into the lining of the abdomen - for example, ovarian cancer. The cancer cells irritate the lining and it makes extra fluid, which builds up in the abdominal cavity.

Ascites can also form if the cancer is blocking the normal blood flow through the liver as this causes a back pressure of fluid. The healthy liver also makes proteins that circulate in the blood. The proteins help to keep fluid in the blood and stop it from leaking out into the tissues. If the liver is damaged, it may not make enough of these proteins and so fluid can leak out and collect in the abdomen or in other parts of the body, such as the feet and ankles. 

Doctors can drain excess fluid from inside the abdomen by putting in a needle. But unless they can stop the fluid from collecting, it will build up again. Sometimes a drug called catumaxomab (Removab) is put into the abdomen to attract immune cells to the tumour area. Doctors can also sometimes put an internal tube under the skin of the abdomen to permanently drain the fluid away. 

It is very common for cancer cells to travel from the site of the original cancer to lymph nodes nearby. This is because there is a natural circulation of tissue fluid from the organs through the lymphatic system. This is not the same as having a cancer of the lymphatic system, such as Hodgkin's lymphoma or non Hodgkin's lymphoma.

When they are operating to remove a primary cancer, surgeons often also remove the group of lymph nodes the cancer is most likely to spread to. Some cancers, such as testicular cancer often spread to the lymph nodes. So your doctor may want you to have preventative treatment, such as radiotherapy to particular areas of lymph nodes.

If cancer spreads to the lymph nodes it may make them swell up. The swollen lymph nodes are easy to see if they are near the surface of the body - for example, in the neck or under the arm. But if the nodes are deeper in the body, they can only be seen on a scan.

Cancer in the lymph nodes may not cause any symptoms. But sometimes, the swollen lymph nodes can block the circulation of tissue fluid. This can cause swelling in the affected part of the body. For example, swollen lymph nodes in the armpit or groin can cause swelling in the arm or leg on the same side of the body. This swelling is called lymphoedema. There is detailed information about lymphoedema on CancerHelp UK.

Some cancers are quite likely to spread to the bones - for example, prostate cancer, breast cancer and lung cancer.

The most common effects of secondary cancer in the bones are

• Pain in the affected bones
• Weakness in the affected bones
• Raised calcium levels in the blood

Pain is caused because the cancer cells multiply in the bone and press on nerves. The growing cancer can weaken the bone by damaging its normal structure. This may mean it is more likely to break. If this happens it is called a pathological fracture. Sometimes these fractures are fixed with an operation to put in a metal pin or attach a metal plate to strengthen the bone.

If you have a bone that has become weakened like this, your doctor will probably suggest you have some radiotherapy. Radiotherapy kills off the cancer cells and the bone begins to strengthen itself. There is detailed information about having radiotherapy for secondary cancer in the bones in the radiotherapy section, prostate cancer section and breast cancer section of CancerHelp UK.

Calcium can be released by damaged bone. If high calcium levels build up in the blood you may

• Feel sick
• Feel tired, drowsy or muddled
• Become constipated
• Feel very thirsty

If the calcium levels become very high they can cause irritability and confusion and eventually unconsciousness. Drugs known as bisphosphonates are available to treat high calcium levels. Bisphosphonates can also sometimes slow or stop the growth of cancer cells in the bone for a while. We have information about blood calcium levels in the coping physically section of CancerHelp UK. 

There is information about symptoms and treatment of secondary bone cancer in our question and answer section.

It is not very common for cancers to spread to the brain, but it can happen. Lung cancer and breast cancer can both spread to the brain. Other cancers can also spread to the brain, including colon (bowel) cancer, kidney cancer and melanoma.

Some types of lung cancer are quite likely to spread to the brain, so your doctor may want you to have preventative radiotherapy treatment to the brain for these types of cancer.

The most common symptoms from cancer that has spread to the brain are headaches and feeling sick. These symptoms are caused because the cancer growing in the brain takes up space. The space for the brain is limited by the skull so the growing cancer causes an increase in pressure inside the skull. This is called raised intracranial pressure. 

Other symptoms depend on which part of the brain the cancer is growing in. And the size of the tumour or tumours. Small secondary brain tumours may not cause very many symptoms at all. Symptoms of secondary cancer in the brain can be any of the following.

• Weakness in an arm, leg, or on one side of the body
• Moodiness or changes in behaviour
• Fits
• Confusion
• Drowsiness
• Vertigo
• Feeling dizzy or unsteady

Secondary cancer in the brain can sometimes be treated. Usually, radiotherapy is used (although this will depend on the type of cancer you have). Steroids are often prescribed to reduce the swelling in the brain and so reduce raised intracranial pressure. Steroids can often make a big improvement in symptoms.

Sometimes cancer cells can start growing in the skin. This is not the same as having skin cancer, melanoma, or cutaneous T cell lymphoma (a type of lymphoma that affects the skin). The secondary cancer may start to grow on or near an operation scar where the primary cancer was removed. Or sometimes secondary skin cancers can grow in other parts of the body.

A secondary skin cancer looks like a pink or red raised lump (a bit like a boil). Skin nodules can be treated. It is important to tell your doctor if you think you have one, because if it is not treated, it may become ulcerated.