Excess of cancer deaths in close relatives of patients with bilateral retinoblastoma.

Cancer deaths among close relatives of 19 patients with bilateral retinoblastoma were reviewed. Altogether 18 deaths of nonocular cancer were found in 5 families. These constitute 5% of the entire material of 365 relatives. The main types of cancer were stomach (6 cases), bronchial (3 cases), urinary bladder carcinoma (2 cases), as well as 2 cases of reticulosarcoma and 1 of leukemia. The retinoblastoma gene may also be associated with higher incidence of cancer in families of retinoblastoma patients.