Childhood cancers: retinoblastoma, a tumor of the retina

Clinical signs and diagnosis of retinoblastoma

Retinoblastoma is a form of eye cancer that affects the cells of the retina. Diagnosis is relatively simple, but sometimes comes too late. The clinical signs, however, such as a white reflection in the pupil or a strabismus, are well known, and an ophthalmological exam must be performed as soon as possible. Early diagnosis determines the use of treatments that will preserve the vision.

Genetic predisposition to retinoblastoma

Half of all retinoblastoma cases occur in individuals who are genetically predisposed to the disease. In these cases, the child carries a constitutional abnormality of the RB1 gene, meaning there is a mutation in all of his or her cells. This abnormality puts the child at a very high risk (90%) of developing retinoblastoma. 

Children who are genetically predisposed to retinoblastoma develop tumors of differing severity and, in rare cases, may not develop tumors at all.

If the inherited RB1 mutation is identified in a person with retinoblastoma, special consultations can take place to offer individual tests to any unaffected relatives (siblings, cousins etc.) who may nevertheless carry the mutation. The aim of this is to carry out ophthalmological monitoring in a specialized environment to screen for possible occurrence of the disease at an early stage.

Effective treatments for retinoblastoma

Institut Curie is the leading treatment center for retinoblastoma in France. Treatments are increasingly effective and differ according to the form of the tumor, its location and size, and the age of the child. The visual prognosis may be compromised, depending on the location of the tumor and the impact of treatment on the retina.

Chemotherapy may sometimes be administered beforehand, to allow possible conservative treatments (when the eye is spared). Several local treatments can then be offered:

• Thermo-chemotherapy, which combines heat and chemotherapy 
• Radiotherapy
• Cryotherapy, which freezes the tumor several times by applying very low temperatures (- 60° to - 80°C)
• Thermotherapy, which involves applying a laser diode beam to the tumor
• Brachytherapy, which uses discs containing iodine grains to radiate the tumor locally.

Enucleation often remains necessary for unilateral forms of the disease, and for one eye in bilateral forms of the disease. For bilateral forms, conservative treatments may be offered for the second eye.

Continuing with research

“In industrialized countries, the vast majority of patients suffering from retinoblastoma are cured. We are striving to reduce the after-effects of treatment,“ explains Prof François Doz, a pediatrician. Therefore, the search for new treatments and improvement of existing ones, to preserve the child’s vision as far as possible, will remain a priority for caregivers and researchers.

Several avenues are being explored. In clinical research, physicians are assessing new therapeutic protocols, especially chemotherapy and radiotherapy, which could reduce the risk of vision loss and secondary cancer. Chemotherapy, like radiotherapy, may have somewhat long-term consequences for the risk of a secondary tumor and, with radiotherapy, for the development of the child’s facial bones during growth.