Radiation therapy for vulvar cancer

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

Radiation therapy is often used to treat vulvar 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:

• shrink a tumour before surgery (called neoadjuvant therapy)
• destroy cancer cells left behind after surgery to reduce the risk that the cancer will come back (recur) (called adjuvant therapy)
• treat lymph nodes in the groin and pelvis
• treat the cancer if you cannot have surgery or chemotherapy because of health problems
• relieve pain or control the symptoms of advanced vulvar cancer (called palliative therapy)

Radiation therapy and chemotherapy may be given during the same time period to treat vulvar 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 vulvar 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.

External radiation therapy is mainly used to treat locally advanced vulvar cancer that has spread to other areas in the pelvis. It shrinks the tumour before surgery, sometimes with chemotherapy, to make the surgery less extensive. This helps avoid disfigurement and loss of function.

External radiation therapy is sometimes used to:

• destroy cancer cells left behind after surgery for early-stage vulvar cancer to reduce the risk that the cancer will come back
• relieve pain or control symptoms for metastatic vulvar cancer that has spread beyond the pelvis

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) 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’s useful for treating tumours in hard-to-reach areas.

Image-guided radiation therapy (IGRT) uses imaging mounted on the linear accelerator to improve the accuracy of radiation therapy. Repeated CT, MRI or PET scans are performed before and during treatment and processed by computers to show changes in tumour size and location compared to the last treatment. This allows the radiation treatment team to adjust your position on the table or the radiation dose to increase accuracy of the treatment. IGRT can lessen the amount of tissue treated and the total dose of radiation received by normal tissue. IGRT may be used to treat tumours in parts of the body that are likely to move, such as the lungs, liver and prostate, or tumours that are very close to vital structures or tissues.

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. A sealed container of a radioactive substance, called an implant, gets placed right into the tumour or in the area where the tumour was removed. The radiation kills the cancer cells over time.

Brachytherapy is sometimes used with external radiation therapy to treat recurrent vulvar cancer.

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 or organs being treated, the total dose of radiation, whether chemotherapy was also given together 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.

Side effects of radiation therapy for vulvar cancer include:

• fatigue
• skin problems
• diarrhea
• radiation cystitis
• nausea and vomiting
• low blood cell counts
• lymphedema
• sexual problems including vaginal narrowing, vaginal dryness and painful intercourse
• treatment-induced menopause

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.