Retinoblastoma

Content

Introduction

Retinoblastoma is a malignant tumor of the eye that develops in the first years of life. It particularly affects the retina, the part of nervous tissue that plays a fundamental role in vision. The nerve cells inside it, in fact, are specialized in the perception of visual signals that are sent to the brain and then processed as images.

Retinoblastoma occurs almost exclusively in children under the age of 4-5 years (1 case for every 18,000-20,000 new borns). In most cases it appears during the first year of life, after 3 years it rarely develops. Only in 2% of people it occurs after age 5 and very rarely in adults. There are no differences between males and females. If found (diagnosed) in the early stages, retinoblastoma can be successfully treated and over 90% of children heals.

Symptoms

The main signs of the presence of retinoblastoma are:

  • white reflection inside the pupil (leukocoria), which can be highlighted in photos with flash. Generally the pupil (central part of the eye) when hit by the flash light appears red due to the blood vessels present, while in the case of retinoblastoma it is white. Sometimes it happens that parents notice this reflex, but the doctor can detect it with a simple eye exam.
  • strabismus, is the second most frequent disorder (symptom) in the case of retinoblastoma

Other symptoms, potentially related to this type of cancer and typical of advanced stage disease, are:

  • poor eyesight
  • ache
  • redness of the white part of the eye
  • differences in the size of the two eyeballs
  • pupil that does not shrinkwhen exposed to strong light

Causes

The underlying causes of the onset of retinoblastoma are currently unknown, but the mechanisms seem quite clear: it was one of the first tumors to be associated with a genetic anomaly (mutation). The onset of retinoblastoma is determined by a defective gene that causes the cells of the retina to multiply rapidly and without control. In particular, there is the inactivation of the RB1 gene, whose product, the RB1 protein, has a control function on the cell growth. In the event of a mutation in the RB1 gene, the protein no longer functions and the cells are free to grow uncontrollably.

Each cell normally has two RB1 genes. As long as at least one functional RB1 gene is present in a cell in the retina, retinoblastoma will not develop. Only when both RB1 genes are defective (mutated or missing) can the containing cell be able to grow out of control.

There are two forms of retinoblastoma:

  • hereditary (15% of cases), the defective (mutated) RB1 gene is inherited from one of the parents. The anomaly in one of the two RB1 genes is therefore already present at birth (congenital) and affects all the cells of the body. Only after an anomaly of the second gene does the disease develop, usually rapidly and often in both eyes ( In hereditary forms there is also an increased risk of developing tumors in other areas of the body since the mutated RB1 gene is also associated with other forms of cancer such as, for example, lung and breast carcinomas
  • sporadic (85% of cases), the mutation of the RB1 gene appears during the development of the fetus and is detected only in the cells of the retina

Diagnosis

The detection (diagnosis) of retinoblastoma occurs with a simple external examination of the eye and is usually confirmed in a specialized referral center. After a "thorough visit in which, in addition to any other cases in the family (family history), potential signs and disorders (symptoms) associated with the disease are also evaluated, the specialist may decide to perform in-depth examinations to confirm or exclude retinoblastoma and, possibly, define the degree of diffusion (staging).

The main tests that are carried out are:

  • retcam, a very high definition computerized image acquisition system that allows you to evaluate the back of the eye and identify the size of any tumor masses. It is not an invasive test and does not use contrast media; uses a lens that is placed in contact with the cornea through the pupillary foramen. Generally, considering the age (generally, as we have said small children) and the need for the person to remain still, the examination is performed under anesthesia
  • computed tomography (CT) and magnetic resonance imaging (MRI), can be useful in determining the presence of a tumor in the eye sockets, optic nerves or other structures of the brain
  • cytological examination of the bone marrow and cerebrospinal fluid and bone scan, investigations that are carried out if the spread of the disease outside the eye is suspected
  • molecular-genetic diagnosis, allows to identify any mutations of the RB1 gene. Cytogenetic analysis (ie of chromosomes) can be performed on peripheral blood lymphocytes and is used to detect part loss (deletion) or rearrangements involving chromosome 13 (zone 13q14.1-q14.2)

The results of the tests carried out to confirm the presence of retinoblastoma allow to assign a stage to the disease (staging). Based onInternational Retinoblastoma Staging System 5 stages can be distinguished (from zero to IV). The first three indicate that the disease is confined within the eye (intraocular), the last two (IVa and IVb) signal the spread outside the eye. Another "classification, called di Murphree, subdivides intraocular tumors on the basis of localization and diffusion, dividing them into groups ranging from group "A" (not very extensive disease) to group "E" (very extensive disease).

Therapy

Retinoblastoma is the most frequent intraocular tumor in pediatric age, it is a rare tumor, so it is important to contact a specialized center that has a good number of cases. Early assessment (diagnosis) guarantees a probability of recovery of more than 95%, with the possibility of maintaining the structures of the eye and sight (read the Hoax).

There are various treatments, the choice of the most suitable treatment (therapy) depends on the extent of the disease, ie whether it is confined to one or both eyes, or if it is spread to other organs. Currently, there are treatment protocols agreed by the scientific community which establish certain treatments according to the stage of the disease; they aim at eliminating the tumor while safeguarding both the eye and sight.

If the tumor is not very large, it is usually eliminated with laser therapy, thermotherapy (heat used as a therapeutic tool) or with cryotherapy (tumor freezing). When the disease is more widespread, the doctor may decide to intervene with chemotherapy (Video) and / or brachytherapy.

Chemotherapy is a very important weapon against retinoblastoma. It is generally administered intravenously so that the drug reaches all areas of the body (systemic administration).Recently, the possibility of administering chemotherapy directly into the eye has been introduced; this allows lower doses to be used, reducing unwanted effects (side effects).

Finally, in the event that the tumor is too large and no other treatments can be used, the doctor may decide to surgically remove the diseased eye, subsequently placing a prosthesis in the eye socket.

Prevention

It is possible, and in the case of very important familiarity, to carry out a genetic study on family members, including the possibility of prenatal diagnosis. In fact, prevention passes through genetic counseling that should be carried out by people with cases of retinoblastoma among family members. Genetic investigations and molecular examinations, carried out during pregnancy (prenatal), allow us to know if family members or the unborn child are at risk of developing a retinoblastoma. If the test is positive, it is important to schedule visits from birth to discover any cancer cells as soon as possible. In fact, if the retinoblastoma is ascertained (diagnosed) very early, when it is still not very extensive, the possibility of treatment and preservation of sight are good.

For the sporadic forms, on the other hand, it is not currently possible to define effective strategies for prevention, since to date no risk factors have been identified on which to intervene.

Complications

People treated for retinoblastoma run the risk that the cancer may recur in or around the eye. For this reason, after the therapies, the doctor schedules frequent follow-up examinations.

Children affected by the hereditary form have a high risk of developing other types of cancer in any part of the body over the years, even after treatment.For this reason, they need to be checked regularly so that other cancers are discovered as soon as possible.

Living with

Being the parent of a child with retinoblastoma or living with the effects of this cancer every day is a difficult experience.

Parents have to make care decisions very quickly and it is therefore important that they trust the team of doctors who are treating their child.

Children with retinoblastoma can have conflicting experiences: on the one hand, the experience of cancer leads them to appreciate life more, but at the same time their vulnerability increases because of their experience. Continuous medical visits, family stress, uncertainty and physical illness can affect their development and emotional well-being. It is important that both children and parents have psychological support during the care process to help them manage all these aspects.

Bibliography

Italian Association for Cancer Research (AIRC). Retinoblastoma

NHS Inform. Retinoblastoma: Children (English)

National Institutes of Health (NIH). Retinoblastoma (English)

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