Radiation for Liver Cancer Treatment

Radiation therapy, or radiotherapy, is a type of cancer treatment that uses high-powered energy beams to break down and destroy the genetic material (DNA) inside rapidly dividing cancer cells. This kills the cancer cells and prevents their uncontrolled division. The beams can come from X-rays or other sources of radiation, such as protons or gamma rays.

Radiation therapy is typically used in people whose liver cancer or tumor(s):

• Cannot be treated surgically or wants a non-operative alternative to surgery
• Cannot be treated with or has not responded to local therapies like ablation and embolization, or instead of ablation or embolization in some cases
• Has spread to other regions of the body, such as the brain
• Consists of large tumors that are causing pain
• Has a tumor thrombus (a collection of liver cancer cells) blocking the portal vein or hepatic veins
• Is small enough to meet the transplant eligibility criteria for a liver transplant (bridging therapy)

Radiotherapy can help control tumor growth, shrink the liver tumor and alleviate symptoms. In some cases, radiation can be a curative therapy by itself. However, it may not be a good option for people with reduced liver function. This is because the high doses of radiation used in radiotherapy can affect healthy liver tissue as well, thereby lowering the liver’s tolerance to radiation.

Radiation therapy can be administered from outside your body or inside your body.

• Internal radiation therapy: Radioactive material that is contained within a catheter, seed implant or other type of carrier is placed directly into or close to the site of the tumor. If a liquid source of radioactivity is used, it is called systemic radiation therapy. Larger doses of radiation can be administered with internal radiation therapy as opposed to external radiotherapy.
• External beam radiation therapy (EBRT): In this type of treatment, high doses of energy beams are emitted from a source outside of the body. This comes in the form of a large machine called a linear accelerator (LINAC), which precisely directs radiation at the body parts where the cancer is located. Similar to the process of undergoing an X-ray, you will lie on a treatment table under the machine.

Radiation therapy regimens typically consist of a set number of treatment sessions given over a period of time. The preferred treatment for liver cancer is stereotactic body radiation therapy (SBRT), which typically consists of 5 or fewer fractions of radiation. Sometimes, radiation is given with more fractions over several weeks. Your doctors will determine the number of sessions you need based on the type and stage of your liver cancer, as well as other health considerations.

There are a few types of radiotherapy used in the treatment of liver cancer.

Radioembolization

Also known as transarterial radioembolization (TARE) or selective internal radiation therapy (SIRT), this technique combines embolization with internal radiation therapy. It involves injecting small beads loaded with radioactive isotope yttrium-90 into the hepatic artery. This blocks the supply of blood to the tumor and delivers a high dose of radiation directly to the tumor in the liver, thereby destroying the cancer cells. This procedure is commonly referred to as Y-90.

Three-dimensional conformal radiation therapy (3D CRT)

3D CRT uses computers and other special techniques to create a 3D image of the tumor and mold radiation beams so that they are tailored to the size, shape and location of the cancer. The beams are aimed at the tumor from more than one direction, which helps to focus the radiation on the cancer cells. This shrinks the tumor whilst limiting radiation exposure to nearby healthy tissues, thereby lowering the risk of side effects.

Intensity-modulated radiation therapy (IMRT)

IMRT is an advanced, specialized form of 3D CRT commonly used to treat many types of cancer. The radioactive rays are broken up into many small, computer-controlled beams that are sculpted to tailor the liver tumor's specific size, shape and location. In contrast to normal 3D CRT, IMRT allows the radiation oncologist to administer radioactive doses of different strengths. This means the tumor can be shrunk more effectively while minimizing damage to surrounding healthy tissue. As such, the risk of certain side effects associated with 3D CRT can be lowered using IMRT.

Stereotactic body radiation therapy (SBRT)

SBRT is a newer external radiotherapy technique that uses very focused beams of high-dose radiation that are precisely and simultaneously aimed at the tumor from multiple different angles. To achieve this, you will be put in a specially designed body frame and a mold of your body near the tumor is made. This maintains your position for each treatment session and ensures that the radiation is aimed at the exact same place each time.

Because SBRT uses higher radioactive doses, treatment can be completed in a shorter time compared to conventional EBRT. You may only need three to eight sessions of SBRT over a few weeks. It also targets liver tumors more selectively, as the center of the liver tumor receives a high dose of radiation, while individual beams traveling through nearby tissues are of a low dose. In this way, surrounding healthy tissues can be well-protected from radiation exposure, thereby leading to fewer side effects.

This highly targeted form of radiotherapy is generally used in cases of early-stage liver cancer or people with small liver tumors awaiting a liver transplant (bridging therapy).

Proton beam radiation therapy

This technique uses high-energy streams of protons to kill liver tumor cells. It can lower the amount of radiation damage to healthy tissues surrounding the tumor.

Short-term side effects

Like other types of cancer treatment, radiotherapy comes with possible risks and side effects. Some of the more common short-term side effects include:

• Skin problems, such as redness and blistering, in the bodily regions receiving the radioactive dose
• Appetite loss
• Nausea and vomiting
• Diarrhea
• Fatigue

These issues typically resolve in the weeks after treatment ends and your doctor(s) can provide you with medication to manage them.

Late effects

Side effects that develop months or years after treatment are rare, but can happen. These are known as late effects. Some late effects related to liver cancer radiotherapy are:

• Chest pain
• Ulcers and bleeding
• Narrow bile ducts

A more severe late effect of radiotherapy is radiation-induced liver disease (RILD). This is very rare with modern radiation techniques. It can occur several months after treatment, and while usually temporary, it can be life-threatening. Some of the symptoms of RILD are:

• Atypical liver function test results, indicating abnormal liver function
• Swelling/enlargement of the liver and spleen
• Fluid buildup in the abdomen (ascites)
• Yellowing of the skin or eyes (jaundice)

If you’ve undergone radiotherapy and find yourself experiencing any RILD-related side effects, please inform your healthcare providers immediately.

Your doctors will take into account several factors when deciding whether you should receive radiotherapy as part of your treatment plan. These include the characteristics of your liver cancer and your overall health.