I-131 MIBG Therapy

WHAT IS IODINE MIBG THERAPY?

MIBG is short for Meta Iodo Benzyl Guanidine. High dose Iodine MIBG Therapy is a novel form of treatment for refractory high risk advanced neuroblastoma, a cancerous tumour that begins in nerve tissue of infants and very young children.

HOW DOES THE TREATMENT WORK?

MIBG concentrates in neuroblastoma cells and can be combined with radioactive iodine (I-131) to deliver targeted radiation therapy to the tumour cells. The beta emitting isotope, I-131, is used to deliver targeted radiation to neuroblastoma cells. The I-131 MIBG is absorbed by tumour cells, which are killed by radiation emitted by the radioactive I-131. While this therapy destroys the tumour cells, it spares the normal, healthy tissue.

There has been extensive research done with this type of treatment for patients with advanced neuroblastomas. Studies have shown that 30-40% of children with relapsed neuroblastoma respond to MIBG Therapy, and this makes it one of the most active agents for relapsed disease. While this therapy doesn’t cure neuroblastoma, the I-131 MIBG allows patients to gain control of their disease and provide the possibility of prolonged disease stabilisation.

WHAT ARE THE POTENTIAL RISKS AND ADVERSE EFFECTS OF I-131 MIBG?

Most of the adverse effects of I-131 MIBG are mild and the therapy is overall well tolerated.

LIKELY ADVERSE EFFECTS (Happens to 21-100 children out of every 100 children)

  • Decrease in the number of red and white blood cells and platelets made in the bone marrow. The patient may need blood and platelet transfusions and sometimes stem cell infusions are necessary.
  • Nausea
  • Dry mouth
  • Salivary gland irritation

LESS LIKELY ADVERSE EFFECTS (Happens to 5-20 children out of every 100 children)

  • Decrease function of the thyroid gland. This causes tiredness, weight gain, and constipation. Lifetime treatment with a medicine to supplement the thyroid gland may be needed.
  • Not being able to get pregnant or father a child.
  • High or low blood pressure during or after the I-131 MIBG infusion.
  • Thinning of hair.
  • Vomiting
  • Infection due to low white blood cells.
  • Fatigue due to low red blood cells.
  • Bleeding/ bruising due to low platelets.
  • Loss of appetite.

RARE ADVERSE EFFECTS (Happens to less than five children out of every 100 children)

  • Pain in the salivary glands or mouth.
  • Decreased function of the adrenal gland. This affects the activity level & growth, causes tiredness, weight changes, and blood pressure changes. The patient may need to take medicine to supplement the adrenal gland.
  • Decreased heart function.
  • Inflation of the liver – some of the radioactive I-131 MIBG is taken up by the liver and there is a possible risk of future liver damage.
  • A second cancer (such as, leukaemia) that is different from the kind of cancer which the patient has now.
  • Trouble breathing due to infection or damage to the lung (overactive thyroid gland).

The patient will need oral medication (Lugol’s Iodine) to prevent thyroid damage from the radioactive iodine contained in the I-131 MIBG compound. This medication will need to be taken before the treatment begins and will continue for a total of three weeks.

HOW IS I-131 MIBG THERAPY ADMINSTERED?

On the scheduled day of the therapy, the patient is admitted to a special room called the Nuclear Medicine Therapy Room or the Radioisotope Therapy Isolation Room. The I-131 MIBG is given through IV canula or by a central venous catheter over three to four hours. And, if required, IV fluids for hydration and other medications may be given.

Most of the I-131 MIBG accumulates in the neuroblastoma cells and the rest is excreted through the urine. Special precaution needs to be taken as this urine is radioactive. Other bodily wastes like saliva are radioactive as well. This makes the people around the patient vulnerable to radiation exposure. Speak to your doctor regarding precautions and safety measures that need to be taken.

The Radioisotope Therapy Isolation Room

Since the caregivers and other attending the patient receiving the I-131 MIBG Therapy are vulnerable to radiation exposure, the patient is admitted to a special high-dose radioisotope therapy isolation room.

The isolation room is a specially constructed room with lead lined walls and floors. Lead minimises the possibility of radiation exposure. The patient’s bed is also surrounded by portable lead sheets. The caregivers are always required to stay behind these lead shields.

The patient’s urine and other bodily wastes are also radioactive. These effluents are discarded through lead-lined pipes and are collected in a specially constructed decay tank submerged underground where they are stored till it’s safe to be released into the sewers.

The waste disposal bins are also lead-lined. The waste, such as soiled linen, diapers etc. are collected daily and taken to a specialised waste storage facility where it’s kept for a period of three months post which the waste can be disposed of as normal medical waste. A Radiation Safety Officer is responsible for monitoring the radiation levels on a daily basis.

WHAT IS THE ROLE OF CAREGIVER DURING AND AFTER THE I-131 MIBG THERAPY?

As a caregiver, the parents will need to play a very important role in providing day-to-day care and support:

  • Assisting the child with bathing and hygiene needs such as brushing teeth
  • Giving all oral medications to the child
  • Providing the child with an emesis basin when the child feels nauseous
  • Helping the child with bathroom needs

The team of doctors and the radiation safety personnel at the centre will work closely with the parents and help them with taking care of the child.

WHAT ARE THE POSSIBLE RISKS TO CAREGIVER(S) OF THE PATIENT GETTING THE THERAPY?

While caring for the patient, the caregivers (parents, and other family members) will be exposed to the radiation. The doctors and technologists assist the caregivers in taking precautions to ensure that the radiation exposure is minimal.

If a caregiver is pregnant, then special precautions are to be taken to avoid contact with the patient during the therapy and for four weeks after the therapy. If the caregiver didn’t know about being pregnant at the time the therapy was being done, and comes to know later, she should speak to a doctor immediately.

HOW CAN THE RADIATION EXPOSURE BE REDUCED FOR THE CAREGIVERS?

To reduce the radiation exposure to the caregivers, the following precautions should be taken:

  • Minimise the time the caregiver spends near the child
  • Maximise the distance between the caregiver and the child as much as possible
  • Parents and other caregivers should stay in the family caregiver area as much as possible.
  • Parents and other caregivers should stay behind the mobile lead shields as much as possible.
  • The caregivers should always wear Personal Protective Equipment (PPE) when touching the child or anything that the child has touched.
  • No visitors other than parents should enter the High Dose Therapy Room.
WHEN CAN THE CHILD GO HOME?

Children treated with I-131 MIBG Therapy usually stay in the hospital for three to five days, and sometimes longer, until their radiation level comes below a specific level. The centre has a Radiation Safety Officer (RSO) who is responsible for checking the radiation levels daily.

Even when the radiation levels come down to a safe level, the child will still have a small amount of radioactivity in the body, and some simple safety precautions need to be followed at home. The RSO will provide detailed discharge instructions on radiation safety at home.

POST DISCHARGE, WHAT ARE THE FOLLOW-UP STEPS?

  • Post discharge, the caregivers need to ensure that the child continues with the Thyroid Protecting Agent (Lugols Solution) as instructed for four weeks.
  • When the child returns homes, he/ she will require a Complete Blood Count (CBC) to be done at least twice a week.
  • It is most likely that the child will require transfusions of platelets and red blood cells for a few weeks following the therapy.
  • If the Neutrophil count drops below 0.75, the child may require GCSF (Granulocyte Colony Stimulating Factor) – GCSF Is a type of growth factor that helps the white blood cells recover after treatment. And depending on count recovery, it may be necessary for the child to have his/ her stem cells reinfused.
  • A follow-up MIBG Scan may be done nine-12 weeks post treatment.
WHY CHOOSE NUCLEAR MEDICINE THERAPY CENTRE AT FORTIS MEMORIAL RESEARCH INSTITUTE (FMRI), GURUGRAM (HARYANA, INDIA) FOR I-131 MIBG THERAPY?

The Nuclear Medicine Therapy Centre at Fortis Memorial Research Institute is one of the very few centres in India whose doctors and technicians have received extensive training in both managing the equipment and following regulatory protocols in administering high-dose MIBG Therapy. The centre is proud to ensure compliance with the regulatory guidelines regarding radiation exposure to both the caregivers and staff – As Low As Reasonably Acheivable (ALARA).