Your blood, bone marrow and cancer drugs

Cancer drugs can affect your bone marrow and blood causing:

  • an increased risk of infection
  • bruising and bleeding
  • breathlessness

But there are treatments that can help.

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 cells.

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.

White blood cells are part of your immune system. There are several types of white blood cells:

  • granulocytes (neutrophils Open a glossary item, eosinophils, and basophils)
  • monocytes
  • lymphocytes Open a glossary item (T cells and B cells)

Neutrophils are your first line of protection against infections. They kill bacteria and fungi. Lymphocytes create antibodies against bacteria and viruses.

When the number of white cells in your blood is low, you are more likely to get infections. This is because there are fewer neutrophils.

When your level of white blood cells is very low, you have a high risk of infection. When your level of neutrophils is low, it is known as neutropenia Open a glossary item (pronounced new-troh-pee-nee-ah).

Treatments can lower your white blood cell levels

Some drugs lower your white blood cell levels. So your white cell count will begin to fall after each treatment.

With some treatments, your blood count can stay low until the treatment ends.

The nadir

You might have treatment every few weeks. That means your white blood cell count will be at its lowest midway between treatments. For example, if you have treatment every 3 weeks, your lowest blood count will be about 7 to 14 days after your treatment. This is called the nadir (pronounced nah-deer).

You might feel very tired. Some people also feel depressed at this time. After the nadir, the level of white blood cells gradually goes up until it is almost back to normal. It is not surprising that many people feel as if they are on an emotional and physical roller coaster.

When it is time for your next treatment, you will have a blood test to check that your blood count is back to normal levels. If it is normal, you will have your next treatment. This will make your blood count drop again.

Antibiotics to fight infection

You might have antibiotics to fight infections during cancer drug treatment.

Your doctor checks your number of white cells with regular blood tests. If you need antibiotics, you might be able to have them as tablets or capsules to take at home. But sometimes you may need to have antibiotics as an injection or drip through a vein (intravenously). You might have to stay in hospital.

Doctors sometimes prescribe antibiotics before you get an infection. This is to try to prevent it from happening. These are called prophylactic antibiotics. Prophylactic (pronounced prof-il-ak-tik) means preventative.

If you think you have an infection

If you get an infection when your white blood count is likely to be low, you must contact your healthcare team urgently. You might need antibiotics straight away.

Your specialist nurse will tell you if you are at risk of infection. They usually give you contact numbers for an emergency advice line. Ring the advice line immediately, day or night, if you have any symptoms of an infection, such as:

  • a sore mouth
  • a high temperature (fever) of above 37.5°C or a temperature below 36°C
  • feeling generally unwell
  • having shivers or flu like symptoms
  • pain passing urine
  • a cough or breathlessness
  • any redness or swelling, for example around a drip site or central line
  • diarrhoea (4 or more loose bowel movements in 24 hours)
  • feeling or being sick

Growth factors for white blood cells

Your doctor might suggest injections of man made (synthetic) blood cell growth factors. This will usually be when your level of white blood cells goes very low.

These growth factors boost the number of white blood cells your body makes. The growth factor used in cancer treatment is granulocyte colony stimulating factor (G-CSF).

There are different types of G-CSF:

  • lenograstim (Granocyte)
  • filgrastim (Neupogen, Zarzio, Nivestim)
  • long acting (pegylated) filgrastim (pegfilgrastim, Neulasta)

These growth factors all work similarly. The treatment usually starts the following day or a few days after you have your cancer drug. You have G-CSF as a small injection under the skin into the fatty tissue of your stomach, arm or leg.

The different types of growth factors are given at different times.

With filgrastim or lenograstim, you have a daily injection for up to 7 days. These are the most commonly used forms of G-CSF.

The pegylated filgrastim releases the G-CSF much more slowly in the body. So, it works over a longer period.  You have it as a single injection after each treatment cycle. This is instead of several daily injections.

Side effects of G-CSF

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

  • bruising, bleeding gums or nosebleeds
  • bone pain in the legs, arms, back or hips
  • feeling or being sick
  • diarrhoea
  • headaches
  • a high temperature (fever) and chills
  • liver changes
  • fatigue and tiredness

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 contain haemoglobin. Oxygen binds to haemoglobin and is carried around the body by the red blood cells. When the level of haemoglobin in your blood is low, it is called anaemia.

When you have anaemia, you can feel very tired. You might also become breathless. This is because the amount of oxygen carried around your body is lower.

Some chemotherapy drugs, targeted cancer drugs and immunotherapy can make you anaemic. During 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. They carry the oxygen around your body to other tissues and organs. After a transfusion, you will feel more energetic, less tired and less breathless.

You might worry about getting an infection from a blood transfusion. Laboratories now screen all blood before you have it. The chances of getting an infection from a transfusion are small.

Red blood cell growth factor (EPO)

Erythropoietin (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 can help you to feel less tired and breathless. Manufacturers can make EPO in the laboratory. This is in larger amounts than we make in our bodies.

EPO has different names. It includes epoetin alfa, beta, and zeta (Eprex, NeoRecormon and Retacrit) and darbepoetin alfa (Aranesp).

The National Institute for Health and Care Excellence (NICE) recommends EPO for treating low red blood cells (anaemia) in people with cancer having chemotherapy.

Taking EPO and its possible side effects

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. 

EPO can cause side effects, like any drug. Possible side effects include:

  • flu like symptoms
  • rashes
  • high blood pressure
  • blood clots
  • joint pain
  • headaches
  • strokes

Platelets help to clot the blood to prevent bleeding.

If the number of platelets in your blood is low, you might:

  • 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.

Platelet transfusion

If your platelet count is very low, you will need 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.

Manufacturers are developing growth factors that can boost the number of platelets in blood. At the moment, doctors don’t use these products to treat low platelets caused by chemotherapy.

Which drugs affect blood cells

Some cancer drugs can slow the production of blood cells by killing them off as they grow and divide.

These can be drugs like:

  • chemotherapy
  • targeted cancer drugs
  • immunotherapy

The white blood cell count usually goes down first. This is 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.

Drugs such as hormone therapies and bisphosphonates are unlikely to affect your blood cells.

Drugs affect people in different ways

Drugs affect people in different ways, and it is not possible to tell in advance who will have side effects. It depends on:

  • which drugs you are having
  • how long you have been taking the drug
  • your general health
  • the dose (amount of drug)
  • the way you have the drug (for example, as a tablet or injection)
  • other drugs or cancer treatments that you are having

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.

  • Put pressure on cuts for longer than usual to stop bleeding.
  • Try to avoid cuts and grazes - wear thick gloves if you are gardening.
  • Wash all fruit and salads well in clean water.
  • Try to eat a healthy diet.
  • Cook food properly and store it at the correct temperatures. Reheat cooked food well to kill off bacteria.
  • When eating out, choose places with a high food hygiene rating.
  • Wash your hands before eating or handling food, after using the toilet and after contact with animals.
  • Let your doctor know if you have pets, so they know about any possible infection risks.
  • Rest when you feel tired and avoid doing too much in the middle of each treatment cycle.
  • Avoid people who are obviously sick, for example, people with chicken pox, shingles, diarrhoea or fever.
  • You do not need to avoid crowded places or stop seeing family and friends unless specifically advised to do so by your healthcare team. Infections during chemotherapy are usually caused by bacteria naturally present in your own body.
When to contact your healthcare team

Call your advice line, GP or specialist nurse immediately if:

  • you get a temperature over 37.5°C or below 36°C
  • you notice any bleeding or bruising

Breakdown of tumour cells (tumour lysis syndrome)

Tumour lysis syndrome can be a complication of having some cancer drugs. It can happen when the drug kills large numbers of cancer cells. It is most common during treatment for high grade lymphoma or acute leukaemia.

When cancer drugs kill the cancer cells, the body breaks down the dead cells. The breakdown of dead cells releases large amounts of substances into the bloodstream. One of these is uric acid. High levels of uric acid can cause kidney damage.

You also have changes to the following levels of chemicals in your  blood:

  • potassium
  • phosphate
  • calcium

These changes can affect your heart or kidneys. Your doctor will closely monitor your blood levels during treatment.

Preventing tumour Iysis syndrome

If you are at risk of tumour lysis syndrome, you usually have:

  • extra fluids before your treatment - a drip of fluids before you start your treatment hydrates your body and flushes out extra chemicals
  • drugs such as allopurinol or rasburicase to help keep the levels of uric acid in your blood stable

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