Diagnosis

Doctors use many tests to diagnose cancer and determine if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. Although a biopsy is the only way to make a definitive diagnosis for most types of cancer, this is usually not possible in the case of retinoblastoma, and the doctor will suggest other ways to make a diagnosis. Imaging tests may be used to find out whether the cancer has metastasized. Your doctor may consider these factors when choosing a diagnostic test:

• Age and medical condition
  
  
• The type of cancer suspected
  
  
• Severity of symptoms
  
  
• Previous test results

The next step after observing any symptoms (see Symptoms) is to have the child examined by a specialist, who will do a thorough ophthalmic examination to check the retina for a tumor. Depending on the age of the child, either a local or general anesthetic is used during the eye examination.

The specialist will make a drawing or take a photograph of the tumor in the eye to provide a record for future examinations and treatment, and may use additional tests to detect or confirm a tumor.

If a newborn has a family history of retinoblastoma, the baby should be examined shortly after birth by an ophthalmologist (a medical doctor who specializes in eye care) who is experienced in treating cancers of the eye.

In addition to a physical examination, the following tests may be used to diagnose retinoblastoma:

Ultrasound. An ultrasound uses sound waves to create pictures of the internal organs. A transmitter that emits sound waves is moved over the child’s body. Tumors generate different echoes of the sound waves than normal tissue does, so when the waves are bounced back to a computer and changed into images, the doctor can locate masses inside the body. The procedure is painless.

Computed tomography (CT or CAT) scan. A CT scan creates a three-dimensional picture of the inside of the child’s body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into the child’s vein to provide better detail. A CT scan helps the doctor find cancer outside of the eye.

Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the brain and spinal column. MRIs may create more detailed pictures than CT scans and provide the specialist with a picture of the inside of the eye and the brain.

MRI or CT scan of the brain. These tests may be recommended to determine if there is an abnormality of the pineal gland (a small gland in the brain). It is recommended that these scans be performed once every six months until the age of five in children with the genetic form of retinoblastoma (those with bilateral disease and those with unilateral disease with a family history of the disease). Very young children with a tumor in one eye who do not have a family history of the disease may also be at risk, and these tests may be recommended. Scans may also be recommended years after treatment for children who have received external-beam radiation therapy, either as a baseline in the event that problems arise, or to determine the cause of a symptom or sign.

Children who are diagnosed with retinoblastoma will be given a complete physical examination. If there are any additional symptoms or abnormal findings, children may also undergo additional tests to determine if the cancer has spread elsewhere in the body.

Blood tests. These tests evaluate the blood and check for problems with the liver and kidneys. The doctor may also look at the blood for changes in chromosome 13. Chromosomes are the part of the cell that contains genes, and in a few cases of retinoblastoma, these genes are either missing or nonfunctional. Molecular analysis of the gene is now possible in a few medical centers to determine changes that are not visible on ordinary chromosome analysis.

Lumbar puncture (spinal tap). A lumbar puncture is a procedure in which a doctor takes a sample of cerebral spinal fluid (CSF) to look for cancer cells, blood, or tumor markers (substances found in higher than normal amounts in the blood, urine, or body tissues of people with certain kinds of cancer.) CSF is the fluid that flows around the brain and the spinal cord. Doctors generally give an anesthetic to numb the lower back before the procedure.

Bone marrow biopsy/aspiration. This procedure is performed to determine if any retinoblastoma cells have spread to the marrow. For this test, a small amount of bone marrow is removed from the hip with a needle and examined under a microscope. A local anesthetic will be given to numb the area before the procedure.

Hearing test. Children with retinoblastoma taking certain chemotherapy (see Treatment) may have their hearing tested (called an audiology test) to make sure the drugs are not causing hearing loss.

To learn more about what to expect during common diagnostic tests, read Cancer.Net: Tests and Procedures.

To learn about the terms used in this section, read the Cancer.Net Feature: Cancer Terms to Know: Newly Diagnosed.