Super high dose chemotherapy is given over several days to completely destroy the cancer.
In the process, the bone marrow (blood cell factory) is also destroyed.
Transplant is used to prevent the life-threatening complications that arise from complete bone marrow failure.
Before super high dose chemotherapy, your child’s normal stem cells or bone marrow is harvested and frozen.
Several days after high dose chemotherapy, the stem cells or marrow is returned as an intravenous infusion, similar to a blood transfusion.
The stem cells or marrow find their way to the bone cavities and begin to produce new, healthy blood cells. This is why transplants are sometimes called “stem cell / bone marrow rescue”.
Sometimes, several rounds of high-dose chemotherapy are given with stem cell rescue after each round. This is called tandem or serial transplant.
When Transplant Is Used
This aggressive therapy is used only when the child has trilateral retinoblastoma or cancer that has already clearly spread outside the eye.
Transplants are not used to treat cancer contained in the eye, or to treat children whose pathology after eye removal surgery shows a high risk of relapse.
Pre Transplant Therapy
Before transplant, your child will receive a course of regular chemotherapy, usually 6 – 9 cycles. Radiotherapy may also be prescribed. If retinoblastoma cells are found in the bone marrow or cerebrospinal fluid after this treatment ends, more chemotherapy may be given before your child can move forward to transplant.
Conditioning
Before the actual transplant, your child will be given super high dose chemotherapy for between 2-5 days. This conditioning treatment aims to kill all remaining cancer cells in the body.
Total body radiation may be used in conditioning. However, this is extremely rare due to associated risks for children with a constitutional RB1 mutation. If radiation is used, it will be given in 2-3 small doses each day for several days.
Conditioning regimens vary between hospitals and research protocols. Remember that different cancers are treated with different drugs, so your child’s conditioning protocol may be different to that of other children treated in the same transplant unit.
Transplant
The actual transplant Is a simple infusion of the stem cells or bone marrow through a central venous catheter or IV cannula. The infusion usually takes between 1-2 hours.
The infusion is given several days after super high dose chemotherapy ends. If it is given too soon, residual chemotherapy may destroy the precious infused stem cells.
The stem cells flow through the bloodstream to the bone cavities, where they begin to rebuild the bone marrow factory. This process is called engraftment and usually takes 3-4 weeks, but can take several months.
Until engraftment, red blood cells and platelets will be transfused to protect against serious bleeding or anaemia. Growth factor (G-CSF)| injections will also be given to help the bone marrow rebuild the immune system faster.
Intensive medical and nursing care is required during this time. Your child will be treated in an isolation room to protect her from infection. One parent will be able to remain with her at all times, following strict infection control measures.
Transplant infusion day is called “Day 0”. Conditioning days are minus days (e.g. “chemo began on day -7”). Days post transplant are plus days (e.g. “she engrafted on day +30”).
