Radiation therapy for soft tissue sarcoma

Radiation therapy uses high-energy rays or particles to destroy cancer cells. It is sometimes used to treat soft tissue sarcoma. Your healthcare team will consider your personal needs to plan the type and amount of radiation, and when and how it is given. You may also receive other treatments.

Radiation therapy is given for different reasons. You may have radiation therapy to:

• destroy the cancer cells in the body
• shrink a tumour before other surgery (called preoperative or neoadjuvant radiation therapy)
• destroy cancer cells left behind after surgery to reduce the risk that the cancer will come back (recur) (called postoperative or adjuvant radiation therapy)
• relieve pain or control the symptoms of advanced soft tissue sarcoma (called palliative therapy)

The following types of radiation therapy are used to treat soft tissue sarcoma.

During external radiation therapy (also called external beam radiation therapy), a machine directs radiation through the skin to the tumour and some of the tissue around it.

External radiation therapy may be given before, during or after surgery. It is usually used for stage 2 and stage 3 soft tissue sarcomas to lower the risk of the cancer coming back where it started (called a local recurrence). For soft tissue sarcoma in an arm or a leg, external radiation therapy can help keep the limb working properly and prevent amputation. When surgery can’t be done, external radiation therapy can be the main treatment.

External radiation therapy is usually given once a day for several weeks. How long treatment is used depends on many factors such as the size and location of the cancer, the dose of radiation, when the radiation is given and your overall health.

Intensity-modulated radiation therapy (IMRT) is a type of external radiation therapy called conformal radiation therapy. It uses a special device to shape and aim many radiation beams at the tumour from different angles. The strength (intensity) of the radiation beams can also be changed. This reduces the amount of radiation that reaches sensitive areas of the brain, such as the optic nerve, the brain stem and the pituitary gland, while allowing a higher dose to be given to the tumour.

Stereotactic body radiation therapy (SBRT) delivers precisely targeted high doses of radiation to tumours in fewer sessions. It creates many beams of radiation from different angles that meet at the tumour. The tumour receives a high dose of radiation, while the individual beams that travel through surrounding tissue are a low dose. This lowers the effects of radiation on healthy tissue surrounding the tumour. SBRT may be used to treat lung metastases when there are only a few small tumours. In certain cases, it may be used to treat metastases outside the lungs.

Find out more about lung metastases.

Internal radiation therapy places radioactive materials in the body. Larger doses of radiation can be given with internal radiation therapy than with external radiation therapy.

Brachytherapy is a type of internal radiation therapy sometimes used for soft tissue sarcoma.

Brachytherapy uses a radioactive material called a radioactive isotope. It is placed right into the tumour or very close to it. Radioactive materials can also be placed in the area where the tumour was removed. The radiation kills the cancer cells over time.

Brachytherapy may be used after surgery instead of external radiation therapy. It may also be used to treat a recurrent soft tissue sarcoma that has been treated with external radiation therapy.

To give brachytherapy for soft tissue sarcoma, the radioactive material is put into tubes (catheters) or special applicators. The applicator is placed into the area where the tumour was removed. It is usually given as high-dose-rate (HDR) brachytherapy. This means that a single high dose of radiation is given over a few minutes. Sometimes a few of these short treatments are given over a few days or weeks.

Brachytherapy usually causes fewer side effects and long-term complications than external radiation therapy. More research is needed to fully compare these treatments.

Radiation oncologists need special equipment to give brachytherapy, so it isn’t available in all treatment centres.

Side effects can happen with any type of treatment for soft tissue sarcoma, but everyone’s experience is different. Some people have many side effects. Other people have few or none at all.

During radiation therapy, the healthcare team protects healthy cells in the treatment area as much as possible. But damage to healthy cells can happen and may cause side effects. If you develop side effects, they can happen any time during, immediately after or a few days or weeks after radiation therapy. Sometimes late side effects develop months or years after radiation therapy. Most side effects go away on their own or can be treated, but some side effects may last a long time or become permanent.

Side effects of radiation therapy will depend mainly on the size of the area being treated, the specific area of the body being treated, the total dose of radiation and when the radiation is given during the treatment schedule. Some common side effects of radiation therapy for soft tissue sarcoma are:

• fatigue
• skin problems, such as redness, blistering and peeling
• less strength and stiff joints in a treated limb
• swelling in a treated limb (called edema)
• thickening and scarring of connective tissue( called fibrosis)
• slow wound healing – mainly when radiation therapy is given before surgery
• nausea and vomiting – more often from radiation to the abdomen
• diarrhea– more often from radiation to the abdomen or pelvis
• difficulty breathing– more often from radiation to the chest or lungs

Tell your healthcare team if you have these side effects or others you think might be from radiation therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

Find out more about radiation therapy and side effects of radiation therapy. To make the decisions that are right for you, ask your healthcare team questions about radiation therapy.