Eyesight, an Insight - Insight - Diseases

The information here applies only to retinoblastoma and not to other kinds of eye cancer.

Retinoblastoma - (Reh-tin-oh-blast-oma) is a cancer of one or both eyes which occurs in young children. There are approximately 350 new diagnosed cases per year in the Unites States. Retinoblastoma affects one in every 15,000 to 30,000 live babies that are born in the United States. Retinoblastoma affects children of all races and both boys and girls.

The eye consists of a sphere called the globe, which is filled with a gelatinous material called vitreous; a lens with an iris like a camera on the front; and the retina in the back. The lens and the iris focus incoming light on the retina. The retina is like the film in a camera. The retina is connected to the brain by the optic nerve.

The pattern of light appearing on the retina is transmitted from the retina to the visual cortex of the brain, allowing us to see. The eyes develop very early as babies grow in the womb. During the early stages of growth, the eyes contain cells that can grow very fast that are called retinoblasts. Later on, the cells stop growing and develop into mature retinal cells.

Rarely, something goes wrong during development of retinal cells. Instead of developing into cells specialized for detecting light, some retinoblasts continue to grow rapidly and out-of-control, and form a cancer known as retinoblastoma.

If growth of these cells is not controlled by treatment, they can form a tumor that fills much of the eyeball. The cells may break off of the retinal tumor and float through the vitreous to reach other parts of the eye, where they form more tumors. If these tumors block the channels that are important in circulation of fluid within the eye, the pressure inside the eye can rise, resulting in glaucoma.

Glaucoma is one of the serious complications of retinoblastoma that can lead to loss of vision in the affected eye. Most retinoblastomas are found and treated before they have spread outside the globe. But, retinoblastoma cells can spread to other parts of the body. The cells sometimes grow along the optic nerve to reach the brain. Retinoblastoma cells can also grow through the covering layers of the globe into the eye socket, eyelids and nearby tissues. Once tissues outside the globe are affected, the cancer may then spread to lymph nodes (small bean-shaped collections of immune system cells) and to internal organs and to bones.

If you break Retino-blast-oma into it's separate components you can begin to get an idea of what it's about.

The Reese-Ellsworth classification system was developed by two physicians as a method to predict prognosis of eyes treated by methods which save or preserve the eye. The higher the Group number in the system, the poorer the chance is of saving the eye.

Reese-Ellsworth Classification for Retinoblastoma

Group I

Group II

Group III

Group IV

Group V

Recently, a staging system was developed to group retinoblastoma tumors confined to the eye and those tumors which spread outside of the eye and in other parts of the body. This system is referred to as the Abramson Staging System for Retinoblastoma. [click here]

A risk factor is anything that increases a person's chance of getting a disease such as cancer. Lifestyle-related risks are the most significant factors contributing to cancers in adults. Examples include the effect of unhealthy diet (high-fat, not enough fruits and vegetables, etc.), not enough exercise, and habits such as smoking and drinking alcohol. Lifestyle-related risk factors have little or no significance to childhood cancer.

Age: The average age of patients with retinoblastoma is 2 years. About eighty percent are diagnosed before age four. Retinoblastomas are extremely rare in adults.
Race: In the United States, retinoblastoma is equally common in all races.
Gender: Retinoblastoma is equally common in boys and girls. Heredity: About 40% of cases of retinoblastoma are hereditary. That is, they are due to a genetic mutation (abnormality of DNA) inherited from one of the child's parents. About 60% of hereditary retinoblastomas are bilateral (affect both eyes) and about 40% are unilateral (affect one eye). Nonhereditary retinoblastomas nearly always affect on eye only.
Hereditary retinoblastomas tend to develop in younger children than sporadic (not hereditary) ones. Most hereditary retinoblastomas are detected by one year of age. The way in which inherited abnormalities of DNA make certain children likely to develop retinoblastoma is explained in the section "Do We Know What Causes Retinoblastoma?"

Unlike many cancers of adults, there are no avoidable risk factors (such as smoking or exposure to hazardous chemicals in the workplace) that influence a child's risk of developing retinoblastoma. Therefore, there is nothing that a parent or child can do to prevent this cancer. And, if a child does develop retinoblastoma, it is important to realize that there is nothing the child and parents did to cause it. The outlook for successful treatment of children with retinoblastoma can be improved by early detection of this cancer. Refer to the section on "Can Retinoblsatoma be Found Early?" for more information.

During the past few years, scientists have made great progress in understanding how certain changes in a person's DNA can cause cells of the retina to become cancerous. DNA carries the instructions for nearly everything our cells do. We usually resemble our parents because they are the source of our DNA. However, DNA affects more than our outward appearance. It influences our risks for developing certain diseases, including some kinds of cancer.

Some genes (parts of our DNA) contain instructions for controlling when our cells grow and divide. Genes that promote cell division are called oncogenes. Others that slow down cell division or cause cells to die at the right time are called tumor suppressor genes. It is known that cancers can be caused by DNA mutations (defects) that activate oncogenes or inactivate tumor suppressor genes. About 40% of children with retinoblastoma have inherited an abnormal Rb tumor suppressor gene from one parent.

About 80% of children who inherit an abnormal Rb gene from a parent develop a retinoblastoma in one or both eyes. When children inherit Rb mutations from a parent, these mutations are present in every cell of the child's body and, therefore, can be detected by testing DNA of blood cells. Because every person has two Rb genes but passes only one of each to their children (the other gene comes from their mate) the odds that a parent will pass their mutated gene on to a child are 1 out of 2.

The remaining 60% of children with retinoblastoma do not have any known inherited gene mutations related to their cancer. Their cancer cells often have changes of the RB gene that are acquired during life rather than inherited before birth. These acquired changes rarely have any apparent cause, and may result from random errors that occur when cells reproduce and divide.

Although scientists are making progress in understanding this process, there are still some points that are not completely understood. It is hoped that a more complete understanding will help in developing ways to better prevent and treat retinoblastoma.

Retinoblastoma can present in a variety of ways. The majority of retinoblastoma patients present with a white pupil reflex or leukocoria instead of a normal healthy black pupil or red reflex similar to the one seen when photographs are taken of a child looking directly into the camera. This abnormal white pupillary reflex is sometimes referred to as a cat's eye reflex. Many times the parent is the first one to notice the cat's eye reflex. Other eye diseases can also present with this white pupillary reflex; leukocoria does not always indicate retinoblastoma. An ophthalmologist can determine the correct diagnosis.

A crossed eye or strabismus is the second most common manner in which retinoblastoma presents. The child's eye may turn out (towards the ear), called exotropia, or turn in (towards the nose), called esotropia.

Retinoblastoma may also present with a red, painful eye, poor vision, inflammation of tissue surrounding the eye, an enlarged or dilated pupil, different colored irides (heterochromia), failure to thrive (trouble eating or drinking), extra fingers or toes, malformed ears, or retardation. On rare occasions, retinoblastoma is discovered on a well-baby examination. Most often, the symptoms of retinoblastoma are first detected by a parent.

After a retinoblastoma is found and staged, the cancer care team will suggest a treatment plan. This is an important decision and it is good to take time and think about all of the choices. Because retinoblastoma is rare, few doctors except those in specialty eye hospitals and major children's cancer centers have much experience in treating these patients.

A team approach is recommended that includes the child's general pediatrician as well as ophthalmologists (doctors who specialize in diagnosis, surgery and other treatments for eye disease), pediatric oncologists (doctors who specialize in treatment of children with cancer using medications, and often coordinate the work of other specialists caring for children with cancer), and radiation oncologists (doctors who specialize in treatment of children and adults with cancer using various forms of radiation). The team also includes other physicians, nurses, therapists and technologists who have essential roles in diagnosis and treatment and assisting in recovery of normal activity after treatment. There is a lot for you to think about when choosing the best way to treat or manage cancer.

Often there is more than one treatment to choose from. You may feel that you need to make a decision quickly. But give yourself time to absorb the information you have learned. Talk to the cancer care team. Look at the list of questions at the end of this piece to get some ideas. Then add your own. You may want to get a second opinion. Your doctor should not mind your doing this. You may not need to have tests done again since the results can often be sent to the second doctor. If you are in an HMO (health maintenance organization), find out about their policy concerning second opinions.

The main types of treatments for retinoblastoma are surgery, photocoagulation (laser surgery), cryocoagulation (freezing), radiation (external beam radiation and brachytherapy), and chemotherapy. Because retinoblastoma is rare, few doctors except those in specialty eye centers and major cancer hospitals have much experience in treating these patients. Children with retinoblastoma and their families have special needs that can best be met by these children's cancer centers. At these centers are teams of specialists who know about retinoblastoma and the unique needs of children with cancer.

This approach gives the child the best chance for recovery and, if possible maintenance of useful vision. Ask your doctor about finding a children's cancer center near you that has expertise in treating babies and children with this very rare form of cancer. Feel free to ask about the services offered at your treatment center. Your doctor or nurse can tell you what is available to help with any problems you or your child might have.

Disclaimer: Any information displayed here is just for educational purposes, and may not be taken as an expert advice and should not be applied in life without consulting your eye doctor/specialist. We here by take no responsiblity of the accuracy of the above content as they have been taken from various sources.