Most patients with non-Hodgkin's lymphoma will have chemotherapy at some time during their treatment. Chemotherapy drugs are also known as 'cytotoxic' drugs - meaning that they are toxic to cells - and target all fast-dividing cells. The aim is therefore to damage and kill all lymphoma cells throughout the body.
There are many chemotherapy drugs. Which chemotherapy programme is used for a patient with non-Hodgkin's lymphoma may depend on many things, including:
Some chemotherapy programmes involve just one drug, others involve a combination of drugs that are given together.
Often, the treatment is given in cycles - for example, 1 week of treatment followed by 3 weeks off, then another week of treatment, and so on. A full course of chemotherapy typically takes several months.
One of the chemotherapy drugs most commonly given is chlorambucil, which is taken as tablets by mouth. This is not usually used in combination with other chemotherapy drugs. Although each lymphoma unit or clinic will have its own schedule, chlorambucil is often given in cycles, with 2 weeks of treatment followed by 2 weeks off, then 2 weeks of treatment, and so on.
Combinations of chemotherapy drugs are often known by the initials of the drugs. Two of the most common combinations are 'CHOP' and 'CVP', which is often called 'COP'. 'CHOP' is a combination of three chemotherapy medications plus prednisolone, and stands for:
CVP', or 'COP', involves just cyclophosphamide, vincristine (Oncovin) and prednisolone.
People whose symptoms are severe may also be treated with steroids, usually prednisolone, to help to bring the symptoms under control quickly. This can be very effective in the short term, but it is not a long-term treatment. Prednisolone and the other corticosteroids are completely different from the steroids that are banned in sport.
There are many different types of chemotherapy drugs, all of which attack cancerous cells with different modes of action. However, all of the drugs that patients could be given to treat non-Hodgkin's lymphoma work on the principle that cancerous cells are much more likely to be dividing at the time of treatment than are normal cells in the body.
The vast majority of cells in the body spend most of the time in a resting state, dividing only when repair to damaged cells is necessary. In contrast, cancerous cells are dividing all the time, which is one of the reasons why they cause so much harm. Chemotherapy drugs aim to exploit that difference, attacking the tumour cells as they divide.
Some of the drugs interact with receptors on the surface of the cells, while others disrupt the normal functioning of DNA, in order to stop them dividing. Often, combinations of chemotherapy drugs are given that attack different stages of the division process, which increases the chances that more cells will be killed.
However, this also explains why the drugs cause side effects. Because chemotherapy is a 'systemic' treatment, in that the whole body is affected at once, the drugs also attack the normal cells of the body that are often dividing. This includes the skin, the lining of the gut and the hair. (See Side effects, below.)
Some chemotherapy drugs are taken as tablets. Others must be given directly into the blood (or 'intravenously'), either through a needle or catheter inserted through the skin into a vein in the arm or, sometimes, through a central line. A central line is a more permanent catheter that is usually inserted into one of the veins at the top of the chest. The advantage of a central line is that there is no need to insert a new needle every time chemotherapy has to be given. Central lines can also be used to draw blood samples.
Some intravenous chemotherapy drugs can be injected straight into the vein from a syringe, but most are given as a 'drip', which means that the drug is first injected into a bag of fluid, and the fluid is then allowed to drip slowly into the vein using the force of gravity.
Many of the combination therapies involve both tablets and intravenous drugs.
Usually, the treatment is given in cycles. Although these vary widely from one lymphoma unit to the next, the period between cycles is usually 3 weeks, with steriods taken over 5 days after the administration of the chemotherapy. A course of chemotherapy typically takes several months, but the duration depends on many factors and will be different for each patient.
Most of the chemotherapy drugs can be given in an outpatients' clinic, and the patient can go home the same day. Sometimes, however, a short hospital stay is needed.
Many people greatly fear the side effects of chemotherapy. However, it is important to remember that:
Many of the side effects result from the effects that the chemotherapy has on the normal cells of the body. Because chemotherapy affects the growth and division of cells, specifically fast-dividing cells, the areas most affected are those areas where the normal cells grow and divide most quickly:
Nausea (feeling sick) and vomiting (being sick) are also very common side effects of chemotherapy. As these effects are largely dependent on the chemotherapy drugs that are used and on the individual patient, it is not always possible to predict who will be affected or to what extent they will be affected. A few people do not suffer at all. These side effects are likely to start from a few minutes to a few hours after the chemotherapy has been given. They can last a few hours or several days - everyone is different. More recently, supportive drugs that can virtually eliminate nausea in patients have been introduced.
Loss of appetite, often with food tasting different from normal, is a very common side effect of chemotherapy. Many people also experience a general feeling of tiredness and lethargy during a course of chemotherapy. Some people also find that they are more irritable than usual.
Another potential side effect results from the fact that, when a cell dies, it is broken down in the body. One of the chemicals produced by this process is a substance called uric acid. Normally the uric acid is dissolved in the urine and then lost from the body.
However, many more cells than normal die in patients who are receiving chemotherapy, resulting in the production of more uric acid than the kidney can remove. When this happens, the uric acid can collect in the blood and crystallises in the kidney as stones, and in the joints, causing a type of arthritis. If this is not treated, it can be quite serious and can even lead to kidney failure.
Allopurinol is a drug that is given at the start of some chemotherapy, either as tablets or via an intravenous injection, to stop the body making uric acid. This keeps the products of cell breakdown in a more soluble form so they are easily, and harmlessly, washed out of the body in the urine. It has few side effects apart from occasional allergic reactions, usually skin rashes.
These sorts of side effects are usually temporary and go away once the chemotherapy has stopped.
Some chemotherapy drugs affect fertility. For example, in women, menstrual periods may become irregular or stop, while, in men, the sperm count may decline. Although this may be temporary, infertility may be permanent with some treatments. If this is a possibility, the patient and doctor should discuss it before treatment. Men may be offered sperm banking in some cases.
Possible permanent effects include long-term effects on the heart, on sensory nerves, and an increased risk of developing another cancer in later life. In all these cases, the long-term risks have to be weighed against the likely benefits of treatment. The patient and the doctor should discuss these issues before treatment.
There are things that can be done to eliminate many of the potential side effects of chemotherapy or to make them more tolerable. These include:
It is important to remember that the doctor will know which side effects are caused by the chemotherapy drug that is being used and what can be done to lessen or eliminate them. Therefore, most patients will not need to follow these suggestions.