What are blood growth factors?
Blood cell growth factors are chemicals made by the body to encourage the growth of blood cells. Growth factors can now also be made in the laboratory and then used as supportive treatments for people having chemotherapy for lymphoma. Supportive treatments are treatments that do not directly treat your lymphoma, but can help to limit the side effects of chemotherapy.
Chemotherapy attacks cells when they are dividing, which is how body tissues grow. Lymphoma cells divide much more often than healthy body cells, so they are more likely to be killed by the chemotherapy drugs than are normal cells.
Some other healthy body cells divide frequently. Some of these are also killed by chemotherapy, which is why chemo causes side effects. Cells at risk include blood cells, particularly white blood cells, which are important in fighting infection. The body naturally replaces these cells, but it takes time. Having treatment with blood cell growth factors can speed up this process.
The growth factor most commonly used for lymphoma is called granulocyte-colony stimulating factor (G-CSF). G-CSF encourages your bone marrow (the spongy part in the centre of some of our larger bones) to make more white blood cells called ‘granulocytes’. Granulocytes called ‘neutrophils’ are particularly important in fighting infection.
Your doctor may mention neutropenia. This is a low neutrophil count, which is common in people having chemotherapy. It means you are at increased risk of getting an infection. Your doctor may give you G-CSF to help your neutrophil count recover more quickly after each chemotherapy treatment.
There are several types of G-CSF that are used as treatment in cancer, including:
- lenograstim (Granocyte®)
- filgrastim (Neupogen®, Zarzio®, Nivestim®, Ratiograstim®)
- a long-acting type of filgrastim called pegfilgrastim (Neulasta®).
You may have growth factor injections if:
- you are having chemotherapy for lymphoma
- you are having chemotherapy before a stem cell transplant
- you are having stem cells collected before a stem cell transplant
- you are donating stem cells to someone else who is having a stem cell transplant
- you have had a stem cell transplant and your white blood cell count is slow to recover.
If you are having chemotherapy or a stem cell transplant to treat your lymphoma, your blood cell counts drop after each treatment. They then rise again before you have the next dose of chemotherapy 2 or 3 weeks later. When your white blood cell counts fall too low, you are at an increased risk of picking up an infection. If you have an infection, your next chemotherapy treatment might need to be delayed until you are well enough to have it.
Your chemotherapy may also be delayed if your white blood cell counts do not recover quickly enough, in time for your next treatment. Your doctor may suggest you have growth factor injections after each chemotherapy treatment. These help your white blood cell counts to rise more quickly, which reduces the time that you are at increased risk of infection.
Some people need to have high dose chemotherapy to treat their lymphoma. After this type of treatment, you need to have a stem cell transplant. High doses of chemotherapy kill the lymphoma cells, but they also kill your blood stem cells. These are the cells that all your blood cells develop from. After you have finished all the chemotherapy, you need a transfusion of stem cells to replace them.
You can have your own stem cells collected (an autologous transplant) or someone else can donate their stem cells to you (an allogeneic transplant). Growth factors encourage your bone marrow to make stem cells in large numbers. They also encourage them to move out of the bone marrow into the bloodstream, where they can be more easily collected. You may have a growth factor treatment if you are having an autologous transplant, or if you are donating your stem cells to someone who is having an allogeneic transplant.
Growth factors are given as subcutaneous injections (injection just under the skin). You have a course of daily injections for up to 14 days. You usually have the first growth factor injection of each course 1–5 days after your chemotherapy.
Subcutaneous injections are straightforward to give. You don’t have to stay in hospital to have them, unless you are already an inpatient. However, you usually have your very first growth factor injection at the hospital even as an outpatient. A small number of people have an allergic reaction to it, so the medical team want to monitor reactions for an hour or so after the injection.
After your first injection, you may be able to give others to yourself at home. If you prefer, a family member or carer may be able to give them to you. Your nurse will show them how. If this isn’t possible, you may be able to have a district nurse visit daily to give them. If you are well enough, you can go to your GP practice and the practice nurse can give the injections to you.
Most people are prescribed growth factor that comes in single use syringes, already filled with the correct dose. If you are having a growth factor injection called lenograstim, you have to mix the drug and draw it up into the syringe yourself. Your nurse will make sure you know how to do this.
Before you inject yourself with a growth factor, wash your hands thoroughly and use a sterile, alcohol-saturated wipe to clean the skin where you are going to give the injection. Your hospital should give you these along with the pre-filled syringes. Next, open the syringe packet and uncover the needle. Pinch some skin, put the needle in, press the plunger and then pull the needle out. Vary where you give the injections each day, so that an area doesn’t become sore or inflamed. Your nurse should tell you what areas are safe to use. Generally, these are the abdomen (tummy), outside of the thighs and top of the arms. Ask your nurse for specific instructions. The hospital should give you a small plastic bin (a sharps bin) to dispose of the used needles and syringes.
A video of how to give a subcutaneous injection is available on the Cancer Research UK website.
If you are having injections at home, you need to store your growth factor in the fridge. You can take a syringe out of the fridge about half an hour before each injection to make it more comfortable to have.
Generally, blood cell growth factors have few side effects. As most people have this drug at the same time as they’re having a course of chemotherapy, it is difficult to separate side effects of chemo from side effects of growth factors.
A complete list of possible side effects is on the patient information leaflet that comes with the drug. Your medical team should give you this leaflet with your syringes and explain all the possible side effects. You should also get a number to call should you have any problems. Call your medical team if you are concerned about any side effects.
The most common side effects of G-CSF are muscle and bone aches and pains. About 1 in 10 people have these moderately and about 3 in 100 have them more severely. A mild over-the-counter painkiller, such as paracetamol, should help. Check with your doctor which painkiller is best for you, particularly if you are on any other medication.
A small number of people have an allergic reaction to G-CSF. This is very unlikely but it is a good idea to know the signs you should look out for. Contact your doctor urgently if you have any of these symptoms after an injection:
- an itchy rash
- swelling of your face, lips, tongue or throat
- difficulty breathing
- feelings of faintness.
Other side effects are fairly rare. Some people can get an enlarged spleen and this can become serious if not picked up. This happens to fewer than 1 in 100 people having G-CSF. Tell your doctor if you have:
- a feeling of fullness or discomfort on the left side of your abdomen, just under your ribs
- pain on the left side of your abdomen
- pain at the tip of your left shoulder.
G-CSF can cause lung problems, particularly if you’ve recently had a chest infection. This happens in fewer than 1 in 100 people. If you develop a cough, raised temperature or difficulty breathing, contact your medical team.
There are no particular precautions to take when on G-CSF. G-CSF increases your levels of white blood cells, but it doesn’t increase red blood cell or platelet levels, which can also be lowered by chemotherapy. Your doctor should monitor all your blood cell levels throughout your course of chemotherapy. If you have anaemia (shortage of red blood cells) or thrombocytopenia (not enough platelets) you may need other treatment.
Contact your medical team if you have signs of abnormal bleeding, including blood in your urine.