At Memorial Sloan Kettering Cancer Center, the treatment of retinoblastoma is customized for each patient, and depends upon the age of the child, the involvement of one or both eyes, and whether or not the cancer has spread to other parts of the body. The main treatment options are as follows:
Intra-arterial chemotherapy is a new treatment for advanced retinoblastoma in which the chemotherapy drug is injected directly into the ophthalmic artery (the blood vessel that leads to the eye). The patient is given general anesthesia by an anesthesiologist. A thin tube is inserted through a blood vessel (the femoral artery) in the groin (the top part of the leg) and threaded up to the ophthalmic artery, where the chemotherapy is then injected into the eye. This method of chemotherapy delivery is designed to minimize the drug’s exposure to the rest of the body and to reduce side effects. The most common drugs used for this treatment are melphalan and topotecan. The average number of treatment sessions is about three for each eye, each session being delivered at four-week intervals. After a successful treatment, the tumors will shrink. If needed, residual tumors may be treated with laser, cryotherapy, or plaque.
Enucleation is the most common treatment for retinoblastoma. During an enucleation, the eye is surgically removed. This is necessary because it is the only way to remove the cancer completely. It is not possible to remove the cancer from within the eye without removing the entire eye.
The removal of the eye is done under general anesthesia. In the operation, the entire eye is removed along with a long piece of optic nerve as one specimen, and is sent to a pathologist for examination under a microscope.
The eyebrow, lids, and muscles of the eye are all left in place. Blinking, tearing, and movement of the brow are not affected from this surgery. The operation takes less than an hour and is not painful. Children go home the same day and are usually examined in the office on the following day when post-operative instructions and care are explained.
A ball of plastic, rubber, or coral is placed where the eye had been so there is no cavity or hole. After the socket heals, it will look like the tissue on the inside of the lip.
The child is fitted for a prosthesis or false eye approximately three weeks after the operation. The prosthesis is made of plastic to look exactly like the other eye. The prosthetic eye does not move as well as a natural eye and tends to move better up and down than it does side to side. And, of course, the prosthetic eye does not see. There is currently no way to transplant or replace an entire eye.
When both eyes are involved, sometimes the more involved or “worse” eye is enucleated, while the other eye may be treated with one of the vision-preserving treatments, such as external beam radiation, plaque therapy, cryotherapy, laser treatment, or chemoreduction.
External Beam Radiation Treatment
External beam radiation has been used since the early 1900’s as a way to save the eye and the child’s vision. Retinoblastoma is sensitive to radiation, and frequently the treatment is successful. The radiation treatment is performed on an outpatient basis five times per week over a three to four week stretch.
Custom-made plaster-of-paris molds are made to prevent the head from moving during treatment and sometimes sedatives are prescribed prior to treatment.
Tumors usually get smaller (regress) and look scarred after external beam radiation treatment but they rarely disappear completely. In fact, they may even become more obvious to the parent as they shrink, because the pinkish-grey tumor mass is replaced by white calcium.
Immediately after treatment, the skin may be sunburned or a small patch of hair may be lost in the back of the head from the beam exit position. Long-term effects can include cataracts, radiation retinopathy (bleeding and exudates of the retina), impaired vision, and there may be temporal bone suppression, characterized by bones on the side of the head which do not grow normally.
Radiation can also increase a child’s risk of developing other tumors outside the eye for those children who carry the abnormal retinoblastoma gene in every cell of their bodies.
Radioactive plaques are disks of radioactive material that were developed in the 1930’s to radiate retinoblastoma. Today, the isotope iodine-125 is used and the plaques are custom-built for each child.
According to New York State radiation safety rules, the child must be hospitalized for this procedure, and he or she undergoes two separate operations (one to insert the plaque and another to remove it) over three to seven days. Following the use of radioactive plaque, long-term effects including cataracts, radiation retinopathy, and impaired vision may occur.
Laser therapy, which includes photocoagulation and laser hyperthermia (A type of treatment in which body tissue is exposed to high temperatures to damage and kill cancer cells), is a non-invasive treatment for retinoblastoma. Lasers very effectively destroy smaller retinoblastoma tumors. This type of treatment is usually done by focusing light through the pupil onto and surrounding the cancers in the eye.
A new delivery system of the laser, called a diopexy probe, enables treatment of the cancer by aiming the light through the wall of the eye and not through the pupil. Our physicians at Memorial Sloan Kettering were the first worldwide to use the dioplexy probe.
Laser treatment is done under local or general anesthesia, usually does not have any post-operative pain associated with it, and does not require any post-operative medications. Laser may be used alone in addition to external-beam radiation, plaques, or cryotherapy.
Cryotherapy freezes smaller retinoblastoma tumors and is performed under local or general anesthesia. A pen-like probe is placed on the sclera adjacent to the tumor and the tumor is frozen. Cryotherapy usually has to be repeated many times to successfully destroy all of the cancer cells.
Cryotherapy causes the lids and eye to swell for one to five days; sometimes the swelling is so much that the children are unable to open their lids for a few days. This can be frightening for the child and parents, but is usually harmless. Eye drops or ointment can be given to reduce the swelling.
Chemoreduction is the treatment of retinoblastoma with chemotherapy. Chemotherapy given intravenously to your child passes through the blood stream, and, if successful, causes the tumors to shrink within a few weeks. Chemotherapy, with one or more drugs, can be given once, twice, or more often.
At Memorial Sloan Kettering, our physicians use only one chemotherapy drug for the treatment of retinoblastoma. This treatment provides the same effect as using two or three chemotherapy drugs, but with reduced toxicity.
Doctors at Memorial Sloan Kettering introduced the concept of periocular chemotherapy, which is given around the eye using carboplatin to treat intraocular cases. This technique attains higher doses of chemotherapy in the eye and lower systemic (full body) doses. In some cases, this treatment may have to be given as many as 11 times.
Depending on the drugs used, the child may or may not be hospitalized during this process. After chemotherapy, the child is re-examined and any remaining tumors are treated with cryotherapy, laser, or radioactive plaque. Systemic chemotherapy alone rarely, if ever, cures intraocular retinoblastoma. Children may require as many as twenty treatments every three weeks.
Although it is rare, retinoblastoma can spread (metastasize) to the brain, the central nervous system, and the bones. In these cases, chemotherapy is prescribed by a pediatric oncologist and is administered through the peripheral blood vessels or into the brain for months to years after initial diagnosis of metastatic disease.
The results have been very promising. A new intrathecal medication (delivered into the fluid that surrounds the brain and spinal cord) is available for patients whose retinoblastoma has spread to the surface of the brain.
Survivorship & Follow-Up Care
Most children with retinoblastoma in the United States — more than 95 percent — survive the cancer and have normal lives. Children with unilateral retinoblastoma have one eye whose sight is not affected even though they may have had one eye removed. It is important for children with vision in one eye to wear protective eyewear during sports and other activities.
Retinoblastoma is a life-threatening disease, but it is rarely a fatal one if treated appropriately. With the correct treatment and appropriate follow-up both for eyes and for cancers in other parts of the body, a child with retinoblastoma has a very good chance of living a long life.
The majority of children with bilateral retinoblastoma retain at least one eye with good vision, and many are able to retain the use of both eyes. However, all children with bilateral disease and the 15 percent of unilateral patients who have the familial form of retinoblastoma will be at much higher risk for other cancers not involving the eyes throughout their lives.
Five years after a retinoblastoma diagnosis, children with the inherited form of the disease are more likely to die from second tumors than from retinoblastoma. The most common second tumors are osteogenic sarcoma (a cancerous tumor which affects the bones), soft tissue sarcomas, and cutaneous melanomas (tumors of the skin, muscle, and connective tissue).
Although the reported incidences of these tumors vary widely, the risk appears to be about 1 percent a year. This risk is also increased by the use of external-beam radiation, although the amount of increase depends on the age at which the child was treated.
Follow-up appointments with an ophthalmologist and a pediatric oncologist are very important when a child is diagnosed with retinoblastoma. Frequency of examinations depends upon the age of the child, the ophthalmologist’s suspicion of new tumors, whether one or both eyes are involved, and the type of treatment that the child has received. Parents are encouraged to talk to their nurse and to call with questions between visits.