Retinoblastoma is cancer that originates in the retina, which is in the back of the eye. The American Cancer Society states that it is the most common eye cancer in children, and is usually associated with mutations in the Rb gene. When there are abnormalities with this gene, cells grow uncontrollably, leading to retinoblastoma. This kind of cancer can be treated in a variety of ways, including chemotherapy.
Significance
Retinoblastoma is a rare cancer, with only close to 300 children in the United States being diagnosed per year, according to the American Cancer Society. Infants and young children are more likely to be diagnosed with retinoblastoma than older children, with the American Cancer Society stating the average age at diagnosis is 2 years old.
Function
Chemotherapy is used in the treatment of retinoblastoma in a variety of situations. If the tumor has not spread outside the eye, chemotherapy may be used to shrink the tumor before using other treatments; this is called chemoreduction, according to the National Cancer Institute. The American Cancer Society describes another way chemotherapy is used for advanced retinoblastoma; high doses of the medication are needed, and it may be injected into tissues around the eye, where it can slowly be absorbed by the eyeball, in addition to intravenous chemotherapy. The last situation involves retinoblastoma that has spread to other areas of the body; intravenous chemotherapy can travel through the bloodstream and kill cancer cells that have metastasized to distant sites.
Types
The American Cancer Society describes one standard chemotherapy regimen for retinoblastoma as including the drugs carboplatin and vincristine; the drug etoposide may or may not be added to this combination. Other drugs used to treat this disease include cisplatin, doxorubicin, teniposide and cyclophosphamide.
Side Effects
Side effects from chemotherapy drugs vary, and not everyone experiences every side effect. Possible side effects can include mouth sores; hair loss; lowered white and red blood cell counts, which can lead to anemia and increased risk of infection; nausea and vomiting and appetite loss. These side effects tend to subside once treatment is over, but there are some side effects that can be delayed or permanent. Cyclophosphamide can harm the bladder, which is why individuals on this drug need to drink extra fluids; doxorubicin can harm the heart even years after treatment, so close monitoring of heart function is typically done while on this drug and post-treatment.
Leukemia Risks
A delayed side effect of doxorubicin, cyclophosphamide and etoposide is an increased risk of developing leukemia, but etoposide is of special interest in individuals treated for retinoblastoma. Etoposide can cause acute myeloid leukemia, although the occurrence is rare, according to the American Cancer Society. The National Cancer Institute states that current studies of etoposide and later development of leukemia have not found any definitive answers, and the exact risk has not been determined.
