Retinoblastoma

Definition:
Retinoblastoma is an eye cancer that begins in the retina — the sensitive lining on the inside of your eye. Retinoblastoma most commonly affects young children, but can rarely occur in adults.

Our retina is made up of nerve tissue that senses light as it comes through the front of your eye. The retina sends signals through your optic nerve to your brain, where these signals are interpreted as images.

A rare form of eye cancer, retinoblastoma is the most common form of cancer affecting the eye in children. Retinoblastoma may occur in one or both eyes.

In the developed world, Rb has one of the best cure rates of all childhood cancers (95-98%), with more than nine out of every ten sufferers surviving into adulthood.

Retinoblastoma is rare and affects approximately 1 in 15,000 live births. In the UK, around 40 to 50 new cases are diagnosed each year.

Most children are diagnosed before the age of five years old. In the UK, bilateral cases usually present within the first year with the average age at diagnosis being 9 months. Diagnosis of unilateral cases peaks between 24 and 30 months.

Classification:
There are two forms of the disease; a heritable form and non-heritable form (all cancers are considered genetic in that mutations of the genome are required for their development, but this does not imply that they are heritable, or transmitted to offspring). Approximately 55% of children with Rb have the non-heritable form. If there is no history of the disease within the family, the disease is labeled “sporadic”, but this does not necessarily indicate that it is the non-heritable form.

In about two thirds of cases,  only one eye is affected (unilateral retinoblastoma); in the other third, tumours develop in both eyes (bilateral retinoblastoma). The number and size of tumours on each eye may vary. In certain cases, the pineal gland is also affected (trilateral retinoblastoma). The position, size and quantity of tumours are considered when choosing the type of treatment for the disease.

Symptoms:
The most common and obvious sign of retinoblastoma is an abnormal appearance of the pupil, leukocoria. Other less common and less specific signs and symptoms are: deterioration of vision, a red and irritated eye, faltering growth or delayed development. Some children with retinoblastoma can develop a squint, commonly referred to as “cross-eyed” or “wall-eyed” (strabismus). Retinoblastoma presents with advanced disease in developing countries and eye enlargement is a common finding.

Depending on the position of the tumors, they may be visible during a simple eye exam using an ophthalmoscope to look through the pupil. A positive diagnosis is usually made only with an examination under anesthetic (EUA). A white eye reflection is not always a positive indication of retinoblastoma and can be caused by light being reflected badly or by other conditions such as Coats’s Disease.

In a photograph, the photographic fault red eye may be a sign of retinoblastoma, if in the photograph it is in one eye and not in the other eye. A more clear sign is “white eye” or “cat’s eye”.

The child’s vision may also start to deteriorate and the eye may become  inflamed and sometimes painful.

In two-thirds of cases the cancer is unilateral (affecting one eye). In the rest it’s bilateral.

In 95 per cent of children, the tumour develops before the age of five. Occasionally, babies are born with a retinoblastoma. There’s an increased risk of developing other tumours later in life.

Causes:
Cause of retinoblastomaIn children with the heritable genetic form of retinoblastoma there is a mutation on chromosome 13, called the RB1 gene.The genetic codes found in chromosomes control the way in which cells grow and develop within the body.  If a portion of the code is missing or altered (mutation) a cancer may develop.

The defective RB1 gene can be inherited from either parent; in some children, however, the mutation occurs in the early stages of fetal development. It is unknown what causes the gene abnormality; it is most likely to be a random mistake during the copy process which occurs when a cell divides.

Inherited forms of retinoblastomas are more likely to be bilateral; in addition, they may be associated with pinealoblastoma (also known as trilateral retinoblastoma) with a dismal outcome. The genetic codes found in chromosomes control the way in which cells grow and develop within the body.

Several methods have been developed to detect the RB1 gene mutations.  Attempts to correlate gene mutations to the stage at presentation have not shown convincing evidence of a correlation

Complications:
Recurrent retinoblastoma
Children treated for retinoblastoma have a risk of cancer returning in and around the treated eye. For this reason, your child’s doctor will schedule follow-up exams to check for recurrent retinoblastoma. The doctor may design a personalized follow-up exam schedule for your child. In most cases, this will likely involve eye exams every few months for the first few years after retinoblastoma treatment ends.

Additionally, children with the inherited form of retinoblastoma have an increased risk of developing other types of cancers in any part of the body in the years after treatment. For this reason, children with inherited retinoblastoma require long-term follow-up with a cancer doctor (oncologist).

Diagnosis:
Tests and procedures used to diagnose retinoblastoma include:

*Eye exam. A doctor who specializes in diagnosing and treating diseases of the eye (ophthalmologist) will likely conduct an eye exam to determine what’s causing your child’s signs and symptoms. For a more thorough exam, the doctor may recommend using anesthetics to keep your child still.

*Imaging tests. Scans and other imaging tests can help your child’s doctor determine whether retinoblastoma has grown to affect other structures around the eye. Imaging tests may include ultrasound, computerized tomography (CT) and magnetic resonance imaging (MRI), among others.

*Consulting with other doctors. Your child’s doctor may refer you to other specialists, such as a doctor who specializes in treating cancer (oncologist), a genetic counselor or a surgeon.

Treatment:
Treatment of retinoblastoma varies from country to country.  The first priority is to preserve the life of the child, then to preserve the vision and thirdly to minimize any complications or side effects of the treatment. The exact course of treatment will depend on the individual case and will be decided by the ophthalmologist in discussion with the paediatric oncologist.

Many treatment options exist, including chemotherapy (administered locally via a thin catheter threaded through the groin, through the aorta and the neck, into the optic vessels), cryotherapy, radioactive plaques, laser therapy, external beam radiotherapy and surgical removal of the eyeball.  Any combinations of these treatments may be adopted.

In recent years, there has been an effort to find alternatives to enucleation and radiation therapy.

Prognosis;
Treatment for retinoblastoma has one of the highest success rates of all childhood cancers – nine out of ten children can be cured.

Prevention:
In most cases, doctors aren’t sure what causes retinoblastoma, so there’s no proven way to prevent the disease.

Prevention for families with inherited retinoblastoma
In families with the inherited form of retinoblastoma, preventing retinoblastoma may not be possible. However, genetic testing enables families to know which children have an increased risk of retinoblastoma, so eye exams can begin at an early age. That way, retinoblastoma may be diagnosed very early — when the tumor is small and a chance for a cure and preservation of vision is still possible.

If your doctor determines that your child’s retinoblastoma was caused by an inherited genetic mutation, your family may be referred to a genetic counselor.

Genetic testing can be used to determine whether:

*Your child with retinoblastoma is at risk of other related cancers
*Your other children are at risk of retinoblastoma and other related cancers, so they can start eye exams at an early age
*You and your partner have the possibility of passing the genetic mutation on to future children

The genetic counselor can discuss the risks and benefits of genetic testing and help you decide whether you, your partner or your other children will be tested for the genetic mutation.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:

http://www.bbc.co.uk/health/physical_health/conditions/in_depth/cancer/retinoblastoma1.shtml

http://en.wikipedia.org/wiki/Retinoblastoma

http://www.mayoclinic.com/health/retinoblastoma/DS00786

http://trialx.com/curebyte/2011/06/02/retinoblastoma-photos-and-a-listing-of-clinical-trials/

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