Radiotherapy is a treatment that uses radiation to destroy cancer cells.
What is radiotherapy?
Radiotherapy uses radiation, that are high-energy x-rays, to kill cancer cells.
The X-rays cause damage to the cell’s DNA (the genetic material of the cell) which makes it impossible for the cancer to repair itself and causes the cell to die. Cancer cells begin to die days to weeks after treatment starts and continue to die for weeks or months after it finishes.
The radiation does not distinguish between cancerous and non-cancerous cells and therefore the surrounding healthy cells are also affected. Normal cells affected by the radiation have a greater capacity to heal themselves than the lymphoma cells.
When is radiotherapy used?
Radiation may be used for several different reasons including to cure the cancer (curative radiotherapy) and to achieve a remission (no detectable cancer). Another reason is to treat the symptoms of the lymphoma (sometimes this might be part of palliative treatment).
Lymphomas that may be treated with radiotherapy include:
- Early stage classical Hodgkin lymphoma
- Advanced Hodgkin lymphoma
- Nodular lymphocyte-predominant Hodgkin lymphoma
- Follicular lymphoma (FL)
- Marginal zone lymphoma (MZL)
- Diffuse large B-cell lymphoma (DLBCL)
Radiotherapy can be given with or without chemotherapy.
Types of radiotherapy
- Intensity-modulated radiotherapy (IMRT)-shapes radiotherapy beams and allows different doses of radiotherapy to be given to different parts of the treatment area. Can reduce side effects and late effects. IMRT is often used to treat cancer that is close to vital organs and structures.
- Involved-field radiotherapy (IFRT)- to treat a whole lymph node area, such as neck or groin.
- Involved-node radiotherapy (INRT) to treat just the affected lymph nodes and small margin around.
- Total body irradiation (TBI)-High energy radiotherapy delivered to the whole body. May be part of treatment before an allogeneic (donor) stem cell transplant to destroy the patient’s own bone marrow, so space is made for new stem cells. TBI also suppresses the immune system.
- Total skin electron radiotherapy-a specialised technique for skin lymphoma that use electrons to treat the whole skin surface
- Proton beam therapy (PBT)- This radiation uses protons instead of X-rays. This radiation beam can target cells more precisely, so less radiation reaches surrounding healthy tissues.
About radiotherapy treatment
Radiotherapy is usually done in dedicated cancer care clinics. Patients will have an initial planning consultation and will then attend as per the doctor’s treatment plan.
Planning radiotherapy includes:
- Computed tomography (CT) scan
- A CT simulator makes a three-dimensional map showing where the lymphoma is and to map where the nearby tissues and organs are.
- Dosimetrists use the information from the simulator to make a treatment plan.
- This is approved by the clinical oncologist
- Marks are made on the skin. These marks are lined up with the x-ray beams during treatment.
The dosage of radiation is split into several treatments. It is spread out so healthy cells have time to repair themselves and more cancer cells are captured if the dose is spread over multiple treatments.
Radiotherapy is normally given daily over 2-4 weeks. It is usually given Monday to Friday with a break on the weekend. The time for each session usually takes 10-20 minutes. Most of the time is spent making sure that the x-ray beams are aligned correctly. The radiation is only given for a few minutes. Patients will not feel anything, but the machine may be very noisy.
What is the radiotherapy dose?
The total dose of radiotherapy is measured in Gray (Gy). The Gray is divided into separate treatments called ‘fractions. The dose of the treatment will depend on which part of the body is being treated and the size of the mass.
Highly trained specialists, called radiation oncologists, will calculate the dose that is right for each patient.
Side effects of radiation
The side-effects of radiation depend on where the radiation is aimed. Radiation given to several areas, especially after chemotherapy, can lower blood cell count and increase the risk of infections. The side effects do not usually happen straight away. They may develop during treatment or days to weeks after treatment finishes.
Most common short-term side-effects:
- Skin changes
- Hair loss
Skin reactions usually occur after 10 days. The skin can become red or darkens and may feel itchy or sore. Sometimes the skin may get very sore and blister and skin reactions can take time to improve. They usually improve about 4 weeks after the treatment is complete.
Things that may help include:
- Wear loose clothes
- Use good quality bed linen
- Use mild washing powder for sensitive skin
- Wash skin gently with a mild soap and pat dry
- Take short, lukewarm baths or showers
- Ask the doctor about skincare products
- Moisturize with approved products
- Avoid alcohol-based products on the skin
- Avoid rubbing skin
- Avoid heating and cooling pads
- Avoid the sun. Wear hat and sunscreen when outdoors
- Avoid swimming pools
Some patients might feel very tired or lack energy when having radiotherapy and this may last for weeks after the treatment is complete. This can be due to the daily travel to the radiotherapy department, being anaemic and because the body is repairing damaged cells.
Things that may help:
- Keeping active may help with lack of energy and falling asleep
- Eat well. Take supplements such as iron and vitamin B12
- Keep a normal sleep pattern
- Try complementary therapies such as relaxation therapy, yoga, meditation, and mindfulness
- Blood transfusion if fatigue is due to anaemia
- Avoid stress where possible
Radiotherapy only causes hair loss in the treatment area. This may be where the radiation beam leaves the body as well as where it enters the body. Hair may start to fall out 2 or 3 weeks into treatment, and it may take several months to grow back once treatment is completed. Sometimes it grows back a different colour and texture.
If radiotherapy is targeting the abdomen it is likely that the stomach will also receive a dose of radiation. Radiation to the stomach will cause nausea and vomiting. Radiation to the brain may also cause nausea. There is an area in the brain called the vomiting centre and this controls nausea and vomiting.
Things that may help:
- Anti-nausea medications
- Complementary therapies such acupressure bracelets
- Avoid fatty, fried, strong smelling food
- Eat small frequent meals
- Drinks lots of liquids
- Try sipping on fizzy drinks such as ginger ale.
- Avoid eating and preparing food when feeling sick
- Try sitting in fresh air when eating
- Relaxation exercises
It is normal to have diarrhoea during or after radiotherapy to the abdomen or pelvis. It may also cause stomach cramps and wind. Radiotherapy side effects tend to build up during the course of radiotherapy and the diarrhoea will probably continue for a few weeks once the treatment is finished.
Things that may help include:
- Eat small meals
- Eat a low-fibre diet
- Avoid eating spicy or fried food
- Avoid milk and alcohol
- Anti-diarrhoea medications
- Medications to help with the cramps
- Drink plenty of fluid so you do not get dehydrated. 1 ½ to 2 litres a day
- Go to the hospital if dehydrated
Once treatment has completed, post treatment staging scans are done to review how well the treatment has worked. The scans will show the doctor if there has been a:
- Complete response (CR or no signs of lymphoma remain) or a
- Partial response (PR or there is still lymphoma present, but it has reduced in size)
If all goes well regular follow-up appointments will be made for every 3-6 months to monitor the below:
- Review the effectiveness of the treatment
- Monitor any ongoing side effects from the treatment
- Monitor for any late effects from treatment over time
- Monitor signs of the lymphoma relapsing
These appointments are also important so that the patient can raise any concerns that they may need to discuss with the medical team. A physical examination and blood tests are also standard tests for these appointments. Apart from immediately after treatment to review how the treatment has worked, scans are not usually done unless there is a reason for them. For some patient’s appointments may become less frequent over time.