Treatment

	Dr. David H. Abramson with nurses Maria Hinton, NP, and Alexis Leitenberger, RN

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

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

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

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.

Metastatic Retinoblastoma

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.