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Radiation therapy uses high-energy rays or particles to destroy cancer cells. Radiation isn't often used to treat bile duct cancer. Still, it might be used in some situations.

How is radiation therapy used to treat bile duct cancer?

Although radiation therapy is not often used to treat bile duct cancer, it might be helpful in some situations. Here are some of the ways it might be used:

After surgery to remove the cancer

This is called adjuvant therapy. It's used to kill any tiny deposits of cancer cells that are left after surgery but are too small to see. Not all doctors agree that adjuvant radiation therapy is helpful.

Before surgery for cancers that might be able to be taken out

Some doctors may use radiation therapy before surgery for certain cancers that are thought to be resectable (removable). This is done to try to shrink the cancer and make it easier to take it out. This is called neoadjuvant therapy. It’s not clear how helpful this is.

As part of the main therapy for some advanced cancers

Radiation therapy can also be used as a main therapy for some patients whose cancer has not spread widely throughout the body but can't be removed with surgery. While treatment in this case does not offer a cure, it may help patients live longer.

As palliative therapy

Radiation therapy is often used to ease symptoms when a cancer is too advanced to be cured. It can help relieve pain or other symptoms by shrinking tumors that block bile ducts or blood vessels, or press on nerves.

There are different types of radiation therapy. External beam radiation therapy (EBRT) is the most common form of radiation used to treat bile duct cancer.

External beam radiation therapy (EBRT)

In this type of radiation therapy, a machine sends x-rays to a specific part of the body to kill cancer cells.

Before your treatments start, the radiation team will take careful measurements to determine the correct angles for aiming the radiation beams and the proper dose of radiation. The treatment is much like getting an x-ray, but the radiation is much stronger. The procedure itself is painless. Each treatment lasts only a few minutes, but the set-up time (getting you into place for treatment) usually takes longer. Most often, radiation treatments are given 5 days a week for many weeks.

These are some of the ways EBRT might be given:

• Three-dimensional conformal radiation therapy (3D-CRT) uses special computers to precisely map the location of the tumor(s). Radiation beams are then shaped and aimed at the tumor(s) from several directions, which makes it less likely to damage normal tissues. It may be used to treat localized intrahepatic bile duct cancers that can't be removed with surgery.
• Intensity-modulated radiation therapy (IMRT) is an advanced form of 3D-CRT. It uses a computer-driven machine that moves around you as it delivers radiation. Along with shaping the beams and aiming them at the cancer from many angles, the intensity (strength) of the beams can be adjusted to limit the dose reaching the most sensitive normal tissues. This lets doctors deliver an even higher dose to the cancer.
• Stereotactic body radiotherapy (SBRT) uses the techniques of 3D-CRT and IMRT, but it gives a high dose of radiation over fewer sessions. A course of SBRT may take a week, while a course of radiation using these other techniques often takes 3 to 6 weeks.

Chemoradiation is when chemotherapy (chemo) is given along with EBRT to help the radiation work better. The main drawback of this approach is that the side effects tend to be worse than giving radiation alone.

EBRT side effects

Some common side effects of ERBT to treat bile duct cancer include:

• Skin changes, ranging from redness to blistering and peeling (in the area being treated)
• Nausea and vomiting
• Diarrhea
• Fatigue (tiredness)
• Hair loss (on the skin in the area being treated)
• Low blood cell counts

Side effects from radiation often start a week or 2 into treatment, and usually get better over time once treatment is over.

Proton beam therapy

In people with bile duct cancer, especially if the cancer is unresectable, proton therapy may be an option. Proton therapy is a type of radiation that uses protons rather than x-rays. A proton is a positively charged particle, which can be targeted specifically to the tumor.  Compared to x-rays, proton therapy beams are less likely to damage surrounding organs. This form of radiation therapy continues to be studied.

Brachytherapy (internal radiation therapy)

This type of treatment uses small pellets of radioactive material that are put next to or right into the tumor. The radiation travels a very short distance, so it affects the cancer without causing much harm to nearby healthy body tissues.

For bile duct cancer, brachytherapy is sometimes done with a thin radioactive wire that's put into the bile duct for a short time. This may be called intrabiliary brachytherapy. Brachytherapy can be used alone, or it may be used along with EBRT. At this time it's mostly used as a palliative treatment.