Radiation therapy for soft tissue sarcoma
Radiation therapy uses high-energy rays or particles to destroy cancer cells. It is commonly 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.
How radiation therapy is used
Radiation therapy may be given before surgery, after surgery or as the primary treatment.
For large tumours or tumours that are difficult to remove, radiation therapy may be given, with or without chemotherapy, before surgery. This is called neoadjuvant, or preoperative, radiation therapy. Radiation given before surgery can kill any cancer cells that have broken away from the main tumour and are in the surrounding tissue. This means that less normal tissue around the tumour needs to be removed with surgery so there are fewer problems with function and appearance. It may mean that the tumour is easier to remove. It also lowers the chance that the tumour will come back, or recur, after treatment. In some types of sarcoma, the radiation will also shrink the tumour. This is also called downstaging the sarcoma.
When radiation therapy is given before surgery, it is usually given at lower doses and to a smaller treatment area. This approach lowers the risk of long-term side effects. But there is a higher chance of short-term side effects after surgery, such as infection in areas treated with radiation therapy. These short-term side effects can be treated.
Radiation therapy may be given after surgery, with or without chemotherapy, to destroy cancer cells left behind and to lower the risk that the cancer will come back, or recur. This is called adjuvant radiation therapy.
Adjuvant radiation therapy may be used to treat:
- high-grade sarcomas
- the area around a tumour when there are cancer cells in the tissue removed along with the tumour (which is called positive surgical margins)
- tumours that have a higher risk of recurrence or metastasis
Radiation therapy is not usually needed after amputation.
Radiation therapy is sometimes used as the main treatment for soft tissue sarcoma. It may be the primary treatment for tumours that are very radiation sensitive or that are in areas where surgery can’t be done safely. It may also be used as the primary treatment for people who are not healthy enough to have surgery. Radiation therapy alone doesn’t have the same benefit as having both radiation therapy and surgery.
When radiation therapy is given as the primary treatment, it usually means that the cancer is not curable. Radiation may control the tumour for a period of time. It may also relieve pain or control other symptoms of advanced soft tissue sarcoma. This is called palliative radiation therapy.
Types of radiation therapy
The following types of radiation therapy may be used to treat soft tissue sarcoma.
External beam radiation therapy
Soft tissue sarcoma is usually treated with external beam radiation therapy. During external beam radiation therapy, a machine directs radiation through the skin to the tumour and some of the tissue around it. Depending on the dose, treatments are given each day, 5 days a week, often for 5 weeks.
The area that needs to be treated with radiation will depend on many factors, including the location of the tumour, the size of the tumour, if surgery has been done and if there are positive surgical margins. It may take several weeks before the incision and nearby area are healed enough after surgery to receive radiation therapy.
IMRT is a form of external beam radiation therapy. The radiation beams are shaped, or modulated, to more exactly target the area that needs to be treated. This allows higher doses of radiation to be given to specific areas while sparing the surrounding tissues.
Brachytherapy is internal radiation therapy. A radioactive material (radioactive isotope) is placed right into, or very close to, the tumour. Radioactive materials can also be placed in the area from where the tumour was removed. The radiation kills the cancer cells over time.
Special applicators are used to give brachytherapy, such as tubes, or catheters, or thin wires. During surgery to remove the tumour, the applicators are placed into the area from where the tumour is removed. Brachytherapy allows for a shorter overall treatment time. Treatment may be given over 4–6 days instead of several weeks. Brachytherapy often requires a hospital stay and bedrest while the treatment is given.
Brachytherapy is sometimes used instead of external beam radiation therapy or may be combined with external beam radiation therapy. Brachytherapy may also be used to treat a recurrent soft tissue sarcoma that has been treated previously with external beam radiation therapy.