Radiation therapy for cervical cancer
Radiation therapy uses high-energy rays or particles to destroy cancer cells. It is sometimes used to treat cervical cancer. 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 may be used as the main treatment for early stage cervical cancer if the woman can’t have surgery for other reasons.
Radiation therapy is often used as part of chemoradiation to treat cervical cancer. Chemoradiation is treatment that combines chemotherapy with radiation therapy. Chemotherapy is given during the same time period as radiation therapy.
Radiation therapy is given for different reasons. You may have radiation therapy to:
- destroy the cancer cells in the body
- destroy cancer cells left behind after surgery and reduce the risk of the cancer coming back, or recurring (called adjuvant therapy)
- shrink a tumour before other treatments such as surgery (called neoadjuvant therapy)
- treat cancer that has come back after the first treatment
- relieve pain or control the symptoms of advanced cervical cancer (called palliative therapy)
In some cases, the doctor may suggest ovarian transposition before having radiation therapy for women who haven’t reached menopause. This surgery moves the ovaries higher up inside the abdomen. Moving the ovaries helps to protect them from damage from radiation, which can cause early menopause.
The following are the types of radiation therapy most commonly used to treat cervical cancer.
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. External beam radiation therapy is used to treat the whole pelvis, the loose connective tissue around the cervix and uterus (called parametrial tissue) and the groups of lymph nodes that cervical cancer may spread to in the pelvis. Treatments are usually given once each day for 5 days each week for about 5–6 weeks.
External beam radiation therapy is the type of radiation used in chemoradiation. The chemotherapy drug used most often in chemoradiation is cisplatin (Platinol AQ).
External beam radiation therapy may also be used before brachytherapy to shrink the tumour so brachytherapy can work better.
If brachytherapy can’t be given, conformal radiation therapy may be used. The type of conformal radiation used is 3-D conformal radiation therapy (3-D CRT) or intensity-modulated radiation therapy (IMRT). These techniques allow doctors to deliver radiation therapy to the tumour with better accuracy and less damage to surrounding tissue. 3-D CRT and IMRT are not available at all treatment centres in Canada.
Brachytherapy is internal radiation therapy. It uses a radioactive material called a radioactive isotope. It is placed inside the body next to the tumour.
Intracavitary radiation therapy
When brachytherapy is used to treat cervical cancer, the radioactive substance is usually put inside a special hollow applicator. This applicator is called an intracavitary implant because it is placed inside the vagina, or through the vagina and cervix into the uterus, or both.
If the woman still has 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. If the woman has already had surgery to remove the cervix and uterus, an intracavitary implant can be placed inside the vagina.
Depending on the procedure, local or general anesthetic is used to make the procedure more comfortable.
Brachytherapy is given in low-dose or high-dose rates. It is usually given 1–2 weeks after external beam radiation therapy.
High-dose rate therapy
High-dose rate (HDR) therapy delivers a high dose of radiation over a very short period of time. A single treatment usually takes 10–15 minutes. Women who have HDR therapy usually have 2–5 treatments, each given a few days apart. In most cases the applicators are removed after each treatment.
Cobalt and iridium are the most common radioactive substances used for HDR brachytherapy to the cervix.
The woman can have HDR therapy done as an outpatient so she can go home the same day. HDR is the most common way that brachytherapy is given in Canada.
Low-dose rate therapy
Low-dose rate (LDR) therapy delivers continuous, low doses of radiation over 1–3 days. In most cases, the applicators are left inside the body until the treatment is done. You’ll be given drugs to manage the pain since the applicators can cause discomfort.
Cesium is the most common radioactive substance used for LDR therapy to the cervix.
Most women who have LDR therapy have to stay in the hospital during the entire treatment. Special safety precautions are taken to protect others from exposure to radiation.
Interstitial radiation therapy
Radioactive materials can also be placed directly into, or very close to the tumour. This is called interstitial radiation therapy.
Interstitial implants may be used to treat some women with cervical cancer. Thin needles containing a radioactive substance are inserted directly into the tumour and surrounding tissue.
Women are more likely to have interstitial radiation therapy if they have a uterus that makes it difficult for doctors to place an intracavitary implant. This may include women with a scarred or irregularly shaped uterus. Women whose cancer has spread to supporting tissue around the cervix and uterus or to the side walls of the pelvis are also more likely to have interstitial radiation therapy.
Radiation therapy is sometimes given during the same time period as chemotherapy for cervical cancer. This is called chemoradiation.
Cisplatin (Platinol AQ) is the most common type of chemotherapy drug used in chemoradiation for cervical cancer. It is given with external beam radiation therapy. Cisplatin may act as a radiosensitizer, which means it allows the radiation to work better. Chemotherapy is usually given once a week while a woman has radiation therapy.