What is retinoblastoma?
Retinoblastoma is a type of cancer that affects the retina, a part of the eye. The retina is a lining at the back of the eye that reflects light to make vision possible. In retinoblastoma, the retinal cells mutate and grow abnormally, causing cancer.
Typically, retinoblastoma occurs in children, with most affected patients being below the age of 5. However, it can go unnoticed and progress into the teenage years. Although it is very rare, it can occur in adults as well.
Approximately 2/5 of cases are hereditary, or germinal, meaning they are caused by a mutation in all the body’s cells, or a mutated gene; this mutation may have been inherited, or have developed during the baby’s growth in the womb. The majority of these cases are bilateral, meaning they occur in both eyes. This mutation also makes developing melanoma (a skin cancer) and osteosarcoma (a bone cancer), as well as certain other cancers, more likely. Since retinoblastoma is autosomal dominant, even one parent carrying the gene means there is a considerably high chance of the child carrying the disease.
Most other cases are unilateral, occurring in only one eye. A definitive cause for this has not yet been determined. While retinoblastoma comprises about 2-4% of all cancers in children, it is still extremely rare, and only approximately 6,000 children develop it each year.
At the moment, there are no known risk factors that lead to retinoblastoma, and therefore, no proven preventative measures that can be taken. External factors like smoking, alcohol consumption, and diet have not been proven to be linked to this type of cancer.
What are the symptoms?
Symptoms can go unnoticed for a very long time until the cancer becomes more developed. However, here are some to watch out for:
- A white colour in the pupil of the eye; this will be especially prominent in dim light or in photos taken with flash
- Distinctive crossing of eyes
- Eyes looking in different directions (strabismus)
- Blindness or poor vision
- Redness and/or swelling of the eye(s)
- A change in the colour of the iris
All of the symptoms will be more noticeable when a light is shone into the eye, or when a photo is taken with the flash on. If you notice several of these symptoms in yourself or your child, talk to your doctor, although they may primarily suggest other, more common, eye conditions as a cause. If retinoblastoma runs in the family, make sure to let your doctor know.
How does diagnosis work?
The initial test carried out is a red reflex test. The doctor will shine a light into the eyes: if it is reflected back red, it indicates that the retina is normal. If it is reflected white, it indicates the presence of a problem like retinoblastoma, or potentially other retinal conditions.
In the case of the former, you may be referred to an ophthalmologist to go through further tests, like another red reflex test, or an ultrasound, which is an imaging test. The doctor may also use anaesthetics to carry out a more thorough eye examination and confirm the presence of retinoblastoma. This may be coupled with MRI and CT scans, especially to detect whether the cancer has spread to the rest of the body.
Can retinoblastoma be treated?
If the cancer is localised (intraocular) – if it has not spread to other organs – it is relatively easier to cure. If it is non-localised (extraocular), it is harder to cure, but there are multiple treatment options available in both cases.
Chemotherapy uses chemicals injected into the body, or taken by pills, to kill the tumour or shrink it so it can be removed via other methods. Shrinking it can also make surgery easier or unneeded. Intra-arterial chemotherapy uses a small tube to inject the chemicals straight to the location of the tumour for more effective treatment.
Radiotherapy uses high energy radiation to kill or shrink the tumour. External radiotherapy directs gamma rays at the location(s) of the tumour(s), but internal radiotherapy involves small discs of radioactive material being placed in the body near the tumour(s) for long-term treatment. This therapy, alongside chemotherapy, can also be used to treat recurring cancer.
Other therapies include:
- Cryotherapy. The tumour is frozen at extremely cold temperatures, killing its cells.
- Thermotherapy. This utilises extreme temperatures, like cryotherapy, but superheats the tumour.
- Laser therapy. Laser beams are directed at the eye and destroy the blood vessels that supply the tumour.
Sometimes, surgery is the best, or only option. Enucleation is the typical surgery carried out. When other treatments cannot be used, or when all sight is lost in one eye, this form of surgery removes the affected eye. An eye implant will be fitted in its place, but sight cannot be regained. This treatment can help prevent the cancer from spreading outside of the eye. Shrinking tumours previously may reduce the need for this.
Side effects of this may be infection and excessive bleeding, but your healthcare team will consider this before carrying out the surgery. Immunotherapy or other immune supplements may be used to reduce the risk of external infections.
Especially for later-stage diagnosed cancers, it’s important to continue monitoring retinoblastoma. The 5-year survival rate is relatively high, particularly for localised cases, but a recurrence should always be tackled as soon as possible.
As with other cancers, talking to a trusted friend or family member can help. Make sure you or your child have a support system to help you get through this cancer. If you can, donate to children’s cancer societies and foundations to fund patients and research on the subject. Wearing a white ribbon symbolises retinoblastoma (alongside lung cancer) awareness, and a gold ribbon symbolises childhood cancer awareness. Share resources and reliable information with friends and on social media, and watch out for symptoms as early as possible.
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