Risk of cancer among offspring of childhood-cancer survivors

Reviewers: Kenneth Blank, MD and John Han-Chih Chang, MD
Source: New England Journal of Medicine, May 7, 1998 338 (19):1339

The successful treatment of childhood cancers has substantially increased the number of cancer survivors who are interested in having children of their own. Overall, greater than one-half of all children with cancer will survive five or more years. With this success oncologists face a the quandary of advising childhood cancer survivors as to the risk of their offspring developing cancer. Few studies have addressed this issue, largely because of the rarity of childhood cancer and the difficulty in following these patients and their offspring.

These obstacles were overcome in a multinational effort, the findings of which are reported in the May 7, 1998 New England Journal of Medicine. Using data obtained from national cancer registries in Denmark, Finland, Iceland, Norway and Sweden, investigators from these countries were able to estimate the cancer risk in offspring of childhood cancer survivors. This impressive collaborative effort found that there was no increased risk of nonhereditary cancer developing in the offspring of survivors of childhood cancer.

Hereditary cancers are, by definition, passed from one generation to the next generations via the genes. Retinoblastoma is the most common hereditary childhood cancer, although most cases of retinoblastoma are not hereditary. Wilms' tumor and neuroblastoma may also be hereditary, and there are several cancer syndromes, which are known to be transmitted throughout the genome, including Li-Fraumeni syndrome and von Hippel-Lindau syndrome. When these hereditary tumors were excluded from the database, the risk of cancer in the offspring of survivors of childhood cancer was 1.3- a slight, non-significant increase when compared to a control population. In other words, based on epidemiological data gathered from the 5,847 offspring followed, 16 cases of cancer were expected which was slightly lower than the number detected 22. Further analysis of the database found that the slight increase in risk of offspring cancer was confined to parents whose childhood cancer was detected before the age of 10.

Based on this study of a population of nearly 20 million people over several decades, the authors conclude that childhood cancer survivors should be encouraged to have children and there is no need to screen their children for cancer over and above the usual screening methods.