What is retinoblastoma
Retinoblastoma is a malignant tumor that begins in the cells of the retina (the part of the eye responsible for vision). These cells multiply in an uncontrolled manner and affect one or both eyes.
It is the most common intraocular tumor of childhood, usually occurring before 5 years of age, accounting for 2.5% to 4% of all pediatric cancers.
Two-thirds of cases are diagnosed before 2 years of age, and 95% before 5 years. This is directly related to laterality and delay in diagnosis. Patients with bilateral disease (in both eyes) are usually diagnosed before their first birthday, while those with unilateral disease (in only one eye) are diagnosed between the second and third year of life.
The two forms of presentation of retinoblastoma are:
- Bilateral or multifocal, hereditary, accounting for 25% of all cases – characterized by the presence of germline mutations of the RB1 gene (which can be inherited from an affected family member, in 25% of cases, or result from a new germline mutation, in 75%); and
- Unilateral or unifocal, accounting for 75% of all cases – 90% of which are non-hereditary and considered sporadic, and the remaining 10% are germline.
In Brazil, childhood retinoblastoma affects 1 in every 20,000 live births, which is twice the incidence recorded in the United States and European countries.
Symptoms and signs of retinoblastoma
The main sign of retinoblastoma is leukocoria, a bright reflection in the affected eye, similar to the glow of a cat’s eyes illuminated at night. This is the reflection of light on the surface of the tumor itself and is often only noticed in certain eye positions, under artificial light, or in photos when the flash hits the eyes.
The child may also have crossed eyes, experience pain and swelling in the affected eye, or lose vision in it, as well as have photophobia (excessive sensitivity to light).
Diagnosis of retinoblastoma
After symptoms are noticed, the child should be examined by a doctor to seek a diagnosis. An eye fundus examination is performed, with the pupil well dilated. Biopsies are generally not performed.
The patient undergoes genetic counseling to identify if the case is hereditary.
Additional imaging studies help in the diagnosis. Among the exams are two-dimensional ultrasound, computed tomography, and magnetic resonance imaging. They are important to check the extraocular extension and differentiate from other causes of leukocoria besides retinoblastoma.
The classification of the tumor’s extent in its presentation is crucial for recognizing the prognosis, defining treatment, and assessing the chances of cure.
Treatment for retinoblastoma
The treatment strategy for retinoblastoma is always aimed at saving the child’s life and preserving vision. Factors that need to be considered for tumors of all sizes are the laterality of the disease, the potential for vision preservation, and the intraocular and extraocular staging of retinoblastoma, i.e., its extent and severity.
Small retinoblastoma tumors can be treated with special methods that allow the child to continue to see normally. In these cases in the early stage, surgery is not performed, only methods that resemble laser and radiotherapy.
More advanced cases can be subjected to different therapeutic approaches. The possible ones are:
- Enucleation surgery (surgical technique for mass removal without dissection of the eyeball);
- Local treatments, such as laser therapy and cryotherapy, combined with chemotherapy;
- Intravitreal and intra-arterial chemotherapy;
- Intravenous chemotherapy;
- Radiotherapy;
- Autologous bone marrow transplant.
Prevention of childhood retinoblastoma
There is no way to prevent the development of retinoblastoma. In families with a history of the disease and the presence of the RB1 gene, special attention should be paid to symptoms so that the child can be taken to the doctor as soon as possible if necessary, and their vision can be preserved. Early diagnosis is key.
