Second cancers

Survivors of the hereditary form of retinoblastoma have a much higher risk for developing other types of cancer throughout their lives. This is because each cell in the body has an abnormal RB1 tumor suppressor gene, which would normally help stop some of these cancers from forming. Most of these cancers are very treatable if detected early, which is why it is very important that these children are followed closely throughout life. The entire body must be carefully examined to avoid missing these second cancers.

The most common secondary cancers among retinoblastoma survivors include:

• Osteosarcoma (a type of bone cancer)
• Soft tissue sarcomas (cancers that develop in muscle, tendons and ligaments, and fatty tissue)
• Melanoma (a type of skin cancer)
• Brain tumors
• Lung cancer
• Lymphoma
• Breast cancer

The risk for these cancers is even higher if any of these parts of the body received radiation during treatment for retinoblastoma. Younger children treated with radiation therapy are more likely than older children to develop side effects such as second cancers or problems with bone growth in the irradiated area. Chemotherapy with certain drugs can also increase the risk of some cancers.

Because of the increased risk these children face, it's important that they're taught about other factors that might increase their risk of cancer as they get older. For example, sun exposure will increase the melanoma risk even further, and smoking will increase lung cancer risk. Of course, these children are also at increased risk of other cancers as they get older, just like children who did not have retinoblastoma.

Children with hereditary retinoblastoma also have a small risk of developing a tumor in the pineal gland within a few years. (This is known as trilateral retinoblastoma.) The pineal gland is a bean-sized structure lying under the middle of the brain. It can have cells similar to retina cells, which is why tumors can start there. This is why doctors often recommend that MRI scans be done regularly for up to 5 years to try to detect such tumors as early as possible.