Radiation therapy for cervical cancer

Radiation therapy uses high-energy rays or particles to destroy cancer cells.

Radiation therapy is sometimes used to treat cervical cancer. Your healthcare team will use what they know about the cancer and about your health to plan the type and amount of radiation, and when and how it is given.

You may have radiation therapy to:

• destroy cancer cells in the body
• destroy cancer cells left behind after surgery to reduce the risk that the cancer will come back (called adjuvant therapy)
• relieve pain or control the symptoms of advanced cervical cancer (called palliative therapy)

Radiation therapy and chemotherapy may be given during the same time period to treat cervical cancer. This is called chemoradiation. Some chemotherapy drugs can help make radiation work better by making cancer cells more sensitive to radiation. Combining chemotherapy and radiation therapy can be more effective than either treatment on its own.

The following types of radiation therapy are most commonly used to treat cervical cancer.

During external radiation therapy, a machine directs radiation through the skin to the tumour and some of the tissue around it. External radiation therapy is also called external beam radiation therapy. It is used to treat the whole pelvis, including the connective tissue around the cervix and uterus (called parametrial tissue) and the lymph nodes. Treatments are usually given once a day, 5 days a week, for about 6 or 7 weeks.

External radiation therapy is the type of radiation used in chemoradiation.

External radiation therapy may also be used to shrink the tumour before a type of internal radiation therapy called brachytherapy. If brachytherapy can’t be given, other types of external radiation therapy may be used.

Doctors may use the following external radiation techniques to accurately target the area to be treated and spare as much surrounding normal tissue as possible.

3D conformal radiation therapy (3D-CRT) has many beams of radiation directed at the tumour. The radiation oncologist uses a CT scan or an MRI to map the exact location and shape of the tumour. The radiation beams are then shaped and aimed at the tumour from different directions to treat the tumour from all angles. Each individual beam is fairly weak and less likely to damage normal tissue. A higher dose of radiation is delivered where the beams meet at the tumour.

Intensity-modulated radiation therapy (IMRT) is similar to 3D-CRT in that it delivers radiation from many different angles to treat the entire tumour. In addition to shaping and aiming the radiation beams, IMRT allows the radiation oncologist to adjust the strength (intensity) of the individual beams. This reduces the dose of radiation reaching nearby normal tissue while allowing a higher dose to be delivered to the tumour. It is useful for treating tumours in hard-to-reach areas.

Find out more about external radiation therapy.

Brachytherapy is a type of internal radiation. It uses a radioactive material called a radioactive isotope. The material is placed right into the tumour, very close to the tumour, or in the area where the tumour was removed.

Find out more about internal radiation therapy.

When brachytherapy is used to treat cervical cancer, the radioactive substance is usually put inside a special hollow applicator called an intracavitary implant. The implant is placed inside the vagina, or through the vagina and cervix and into the uterus, or both. This is called intracavitary radiation therapy.

If the cervix and uterus have been removed, the implant can be placed inside the vagina. If you still have a uterus, a rod-shaped applicator called an intrauterine tandem is placed inside the uterus and 2 smaller applicators are placed in the vagina. Sometimes just the tandem is used. Depending on the procedure, local or general anesthetic is used.

Intracavitary radiation therapy is usually given 1 to 2 weeks after external radiation therapy. In early-stage cervical cancer, intracavitary radiation therapy may be used alone.

High-dose-rate (HDR) therapy delivers a high dose of radiation over a very short period of time. A single treatment usually takes 10 to 15 minutes. HDR therapy is usually given in 2 to 5 treatments, with a few days between each treatment. The applicators are usually removed after each treatment.

• Cobalt and iridium are the most common radioactive substances used for HDR therapy to the cervix.
• You can have HDR therapy done and go home the same day.

Low-dose-rate (LDR) therapy delivers a continuous, low dose of radiation over 1 to 3 days. In most cases, the tandem, applicators or implant are left inside the body until the treatment is done.

• Cesium is the most common radioactive substance used for LDR therapy to the cervix.
• You may have to stay overnight in the hospital during LDR therapy. Special safety precautions are taken to protect others from exposure to radiation.

Radioactive materials can also be placed directly into, or very close to, the tumour. This is called interstitial radiation therapy.

Interstitial radiation therapy is sometimes used to treat cervical cancer. Thin needles containing a radioactive substance are inserted directly into the tumour and surrounding tissue.

You are more likely to have interstitial radiation therapy if you have a uterus that makes it difficult for doctors to place an intracavitary implant, such as a scarred or irregularly shaped uterus. You are also more likely to have interstitial radiation therapy if you have cervical cancer that has spread to tissue around the cervix and uterus or to the side walls of the pelvis.

Chemotherapy may be given with external radiation therapy to make the radiation therapy work better. This is called chemoradiation.

Cisplatin is the chemotherapy drug most commonly used in chemoradiation for cervical cancer. It may also be combined with 5-fluorouracil. If cisplatin alone is used, it is usually given once a week during the radiation therapy schedule. If cisplatin and 5-fluorouracil are used, they are usually given every 4 weeks during radiation therapy.

During radiation therapy, your healthcare team protects healthy cells in the treatment area as much as possible. Side effects of radiation therapy will depend mainly on the size of the area being treated, the specific area being treated, the total dose of radiation, if chemotherapy is given at the same time (chemoradiation) and the treatment schedule. Tell your healthcare team if you have side effects that you think are from radiation therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

These are common side effects of radiation therapy for cervical cancer:

• fatigue
• skin problems including irritation of the vagina and vulva
• diarrhea
• nausea and vomiting
• bladder problems including bladder discomfort and the urge to pee often
• low blood cell counts
• lymphedema
• osteoporosis
• sexual problems

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.