Your blood, bone marrow and cancer drugs | Cancer Research UK
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What bone marrow is

Bone marrow is a spongy material that fills the bones. 

Diagram of bone marrow

It contains early blood cells, called stem cells. These develop into the 3 different types of blood cell.

Diagram of three different types of blood cell

Normally stem cells in your bone marrow keep dividing to make new blood cells. This keeps the numbers of cells circulating in your blood within a normal range. When doctors measure the number of blood cells you have, they call this your blood count.


Which drugs affect blood cells

Some cancer drugs can slow the production of blood cells by killing them off as they grow and divide. Chemotherapy drugs and some biological therapies can reduce your red cell, white cell and platelet counts. The white blood cell count usually goes down first, because these cells have the shortest life span in the blood. So if your bone marrow isn't making new ones, the numbers start to drop after a few days.

Hormone therapies and bisphosphonates are very unlikely to affect your blood cells.

Our cancer drugs section has a separate page about each individual cancer drug, so you can see whether your treatment is likely to cause any changes in your blood cells. Even if a drug can cause a drop in blood cells, it may not affect you that way. Drugs affect people in different ways and it is not possible to tell in advance who will have side effects. It depends on

  • The drug or combination of drugs you are having
  • The dose
  • How you react to the drug
  • How you have reacted to drug treatment in the past

White blood cells

White blood cells are part of your immune system. They fight infections. When the number of white cells in your blood is low, you are more likely to get infections because there are fewer white cells to fight off bacteria. If your level of white blood cells is very low you have a high infection risk. This is known as neutropenia (pronounced new-troh-pee-nee-ah).

If you are having a drug that lowers your white blood cell levels, your white cell count will begin to fall after each treatment. If you are having daily treatments your blood count will stay low until the treatment ends.

If you have treatment every few weeks, your white blood cell count will be at its lowest mid way between treatments. For example, if you have treatment every 3 weeks, then your lowest counts will be at about 7 to 14 days after your treatment. This is called the nadir (pronounced nah-deer). You will probably feel very tired. Some people also say they feel depressed at this time. After the nadir, the level of white blood cells gradually goes up until it is almost back to normal. Then, it is time for your next treatment and they will go down again. It is not surprising that many people feel as if they are on a roller coaster, emotionally as well as physically, when having some types of cancer drug.

You may have antibiotics to fight infection during your chemotherapy or biological therapy treatment. Your doctor checks your number of white cells with regular blood tests. If you need antibiotics you may be able to have them as tablets or capsules to take at home. But sometimes you may need to have antibiotics given directly into the bloodstream (intravenously) in hospital.

Sometimes doctors prescribe antibiotics before you get an infection, to try to prevent it from happening. These are called prophylactic antibiotics. Prophylactic (pronounced prof-il-ak-tik) just means preventative.

If you get an infection when your white blood count is likely to be low, you must contact your doctor urgently because you may need antibiotics straight away. Your specialist will tell you if you are at risk of infection and should give you contact telephone numbers for emergencies. Ring immediately, day or night, if you have any symptoms that suggest you might be developing an infection, such as


Growth factors for white blood cells

If your level of white blood cells goes very low, your doctor may decide to give you injections of man made (synthetic) blood cell growth factors. These growth factors boost the number of white blood cells your body makes. The growth factor used in cancer treatment to boost white blood cells is granulocyte colony stimulating factor (G-CSF). There are different types of G-CSF including

  • Lenograstim (Granocyte)
  • Filgrastim (Neupogen, Zarzio, Nivestim, Ratiograstim)
  • Long acting (pegylated) filgrastim (pegfilgrastim, Neulasta)

These growth factors all work in a similar way. The treatment usually starts a few days after you have your cancer drug. You have G-CSF as a small injection into the fatty tissue of your stomach, arm or leg. With filgrastim or lenograstim you have a daily injection for up to 7 days. The pegylated filgrastim releases the G-CSF much more slowly in the body so that it works over a longer period. You have pegylated filgrastim as a single injection after each treatment cycle instead of a number of daily injections.

All treatments cause side effects but the side effects of G-CSF are usually quite mild. They can include

If you have any of these side effects tell your doctor or specialist nurse. They may be able to give you medicines to help.


Red blood cells

Red blood cells contain haemoglobin which carries oxygen around the body. If the level of haemoglobin in your blood is low this is known as anaemia. You can feel very tired. You may also become breathless because the amount of oxygen carried around your body is lower. Some chemotherapy drugs and biological therapies can make you anaemic.

During chemotherapy or biological therapy treatment you have regular blood tests to check the number of red cells in your blood. You can have a blood transfusion if they are very low. The new red cells in the blood transfusion pick up the oxygen from your lungs and carry it around your body to other tissues and organs. After a transfusion you will feel more energetic, less tired and less breathless.

Some people worry they may get an infection from a blood transfusion. All blood is now very carefully screened before it is used. The chances of getting an infection from a transfusion are tiny.


Red blood cell growth factor (EPO)

Erythropoietin (or EPO) is a natural growth factor made by the kidneys. It encourages the bone marrow to make more red blood cells. In certain circumstances, EPO may help you to feel less tired and breathless. EPO can be made in the laboratory in larger amounts than we make naturally in our bodies. Its names include epoetin alfa, beta, theta and zeta (Eprex, NeoRecormon) and darbepoetin alfa (Aranesp).

The National Institute for Health and Care Excellence (NICE) says that women with ovarian cancer who have had chemotherapy with platinum drugs such as  carboplatin or cisplatin can have EPO. NICE also says EPO can be used in people with other cancers who have severe anaemia due to cancer treatment but can't be given blood transfusions. They decided this because the evidence from research suggests that it is only these groups who are likely to benefit from this type of treatment.

You have EPO as an injection just under the skin (subcutaneous injection). How often you have the injection depends on your situation and level of anaemia. You may have it 3 times a week, once a week or every 3 weeks.

EPO can cause side effects, like any drug. The possible side effects include

  • Flu symptoms
  • Rashes
  • High blood pressure
  • Blood clots

Some studies seem to show that EPO may not be safe for people with breast cancer, head and neck cancers, or cervical cancer. You can ask your doctor whether it may be helpful for you. There is more information about EPO in the treating cancer fatigue section.


Cells that help the blood to clot (platelets)

Platelets help to clot the blood to prevent bleeding. If the number of platelets in your blood is low you may

  • Bruise easily
  • Bleed more than usual, even from small cuts or grazes
  • Have nosebleeds
  • Have a rash of small purple or red dots

The rash is called purpura and is caused by bleeding within the skin. If your platelet count is very low you will need to have a platelet transfusion in hospital. You have a drip of a clear fluid containing platelets. It takes about 15 to 30 minutes for each bag of platelets to go through into your vein. The new platelets start to work right away. You can have a platelet transfusion in hospital as often as you need one. Growth factors are being developed that may boost the number of platelets in your blood. These are not yet used routinely.


Breakdown of tumour cells (tumour lysis syndrome)

Tumour lysis syndrome can be a complication of having some cancer drugs. It is most common during treatment for high grade lymphoma or acute leukaemia. When the cancer drugs kill off the cancer cells, the body breaks down the dead cells. Chemicals in the cells are suddenly released into your blood. So the normal balance of chemicals circulating in your blood suddenly changes. Chemicals such as potassium, sodium, phosphates and urea have to be kept within very tight limits in your bloodstream to keep you healthy. Abnormal levels of these chemicals can upset your heart rhythm and the way your kidneys work.

If you are at risk of tumour lysis syndrome, you may have extra fluids before your treatment and certain medicines to help prevent it. A drip of fluids before you start your treatment helps to flush any extra chemicals out of your body. Drugs such as allopurinol and rasburicase can also help to keep the chemical balance of your blood stable. Regular blood tests throughout your treatment will also help to make sure everything is OK.


If you have low blood counts

There are precautions you need to take if you have a low blood count due to cancer drug treatment. You need to

  • Tell your doctor or specialist nurse immediately if you get a temperature over 38° Centigrade (100° Fahrenheit)
  • Tell your doctor or nurse straight away if you notice any bleeding or bruising
  • Keep as clean as you can – for instance, wash your hands before preparing food or eating
  • Try to eat a healthy diet
  • Wash all fruit and salads well in clean water
  • Make sure cooked food is properly heated through to kill off bacteria
  • Try to avoid cuts and grazes – for example, if you are gardening wear thick gloves
  • Keep away from animals to avoid infection, especially cat litter trays and bird cages
  • Let your doctor know if you have pets, so they know about any possible infection risks
  • Put pressure on cuts for longer than usual to stop bleeding
  • Rest when you feel tired
  • Avoid doing too much in the middle of each treatment cycle, as your blood counts will be low and you may feel very tired
  • Avoid contact with anyone who has (or may have been) exposed to chicken pox
  • Let your doctor know if you think you may have been close to anyone with chicken pox

More information about cancer treatments

Our cancer treatment section has detailed information about cancer drugs. Some of the organisations on our general cancer organisations list can send you books and information about cancer treatments. Some of these are free. You can find details of books, booklets and leaflets about cancer treatments on our cancer treatment reading list.

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Updated: 5 August 2014