Introduction: Retinoblastoma represents only 3% of paediatric cancers, but it is the most prevalent intraocular tumour in this population. It develops in the retina as a primitive neuroectodermal tumour that affects development during gestation. The tumour presents in two different forms depending on whether or not it expresses a genetic modification. For patients diagnosed at preschool age, 75% are unilateral non-hereditary cases. While enucleation is the preferred treatment for advanced stages of the tumour, other modalities, such as systemic and intraocular chemotherapy, radiotherapy and local treatments with thermotherapy, cryotherapy, and brachytherapy can be used to try to preserve the eye. However, applying radiation therapy treatments increases the risk of secondary tumours.
Objective: To analyse the results obtained from patients with a retinoblastoma diagnosis at the Costa Rica National Children’s Hospital (HNN) Oncology Unit who received external beam radiation therapy and other therapeutic modalities during the period from January 2009 to December 2015.
Materials and methods: Data were extracted from the patient’s medical records and entered in a data collection instrument. We then analysed the results and formulated conclusions.
Results: A total of 36 patients were evaluated. This corresponded to 45 cases or the number of eyes affected by bilateral presentation of retinoblastoma. The documented incidence was 0.83 cases per 10,000 live births and the majority were female preschool-age children. Of these, 40% presented bilaterally and 13% were of hereditary origin. Up to 78% of these cases were diagnosed with advanced stage D and stage E. All patients who received conservative treatment progressed, requiring up to four lines of treatment. Eight patients, all in the most advanced stage, received external beam radiation due to the failure of other modalities. The main adverse effects observed were radiodermatitis, facial hypoplasia and conjunctivitis. Additionally, we report the emergence of a secondary neoplasm in two patients, one post-chemotherapy and the other post-radiotherapy.
Conclusions: Advanced-stage patients who initially received conservative treatments responded more poorly than those treated more aggressively with surgery alone or with surgery combined with another treatment modality. Treatment with radiation therapy was used in 22% of the cases (8 patients) and all patients treated with radiotherapy showed some adverse effects.