Retinoblastoma is a rare form of eye cancer that primarily affects young children. This condition originates in the retina, the light-sensitive tissue at the back of the eye. The retina captures light and converts it into signals sent to the brain, enabling vision. While rare, it is the most common childhood eye cancer.
Understanding the Types and Causes
Retinoblastoma presents in two forms: heritable and non-heritable. Heritable retinoblastoma, about one-third of all cases, involves a germline mutation in the RB1 gene. This mutation can be passed down from a parent and often results in tumors in both eyes, known as bilateral retinoblastoma.
Non-heritable, or sporadic, retinoblastoma makes up the remaining two-thirds of cases and is not inherited. In these instances, the RB1 gene mutation occurs spontaneously in a single retinal cell after birth, leading to a tumor in only one eye, referred to as unilateral retinoblastoma. The RB1 gene normally produces a protein that helps regulate cell growth. When both copies of this gene are mutated, retinal cells can grow uncontrollably, forming a tumor.
Identifying the Signs
Early identification of retinoblastoma is beneficial for treatment outcomes. The most common sign is leukocoria, a white pupil reflex. This white appearance, noticeable in dim light or flash photography, occurs when light reflects off the tumor’s surface.
Another common indicator is strabismus, where the eyes appear misaligned. Other less frequent signs include poor vision, redness, or swelling of the eye. If these symptoms are observed, a dilated eye exam performed by an ophthalmologist is the first step in diagnosis. Further diagnostic procedures may include imaging tests such as ultrasound or MRI, which provide detailed images of the eye and surrounding structures. Genetic testing can determine if the condition is heritable.
Navigating Treatment Options
The primary goals of retinoblastoma treatment are to save the child’s life, preserve the affected eye, and maintain as much vision as possible. Treatment approaches vary depending on the tumor’s size, location, and whether it has spread. Chemotherapy is a common modality, administered systemically, directly into the eye’s artery (intra-arterial), or into the vitreous humor (intravitreal) to shrink tumors.
Focal therapies are used for smaller tumors or in conjunction with chemotherapy. These include laser photocoagulation, which uses a focused laser beam to destroy tumor cells with heat, and cryotherapy, which uses extreme cold to freeze and eliminate cancerous tissue. Thermotherapy, another heat-based treatment, also targets and destroys tumor cells.
Radiation therapy can be employed, either as external beam radiation, delivered from outside the body, or brachytherapy, which involves placing a small radioactive plaque directly on the eye near the tumor. In cases where the tumor is large, has spread, or has not responded to other treatments, enucleation, the surgical removal of the eye, may be necessary to prevent the cancer from spreading further.
Life After Diagnosis
Following a retinoblastoma diagnosis and treatment, long-term follow-up care is important. This care involves regular eye examinations to monitor for any recurrence of tumors or the development of new ones, especially in children with the heritable form of the disease. For individuals with heritable retinoblastoma, there is a slightly increased risk of developing other types of cancers later in life, such as sarcomas or melanoma, necessitating ongoing screenings.
Children who have undergone treatment may experience some degree of vision impairment, depending on the extent of the disease and the type of treatment received. If an eye has been removed, a prosthetic eye can be fitted, which provides a natural appearance. Modern treatments and early detection lead to positive outcomes, with a high overall survival rate for children diagnosed with retinoblastoma.