Is There an Increased Risk of Cancer in Children of Survivors of Childhood Cancer?
ABSTRACT & COMMENTARY
Synopsis: Long-term follow-up of nearly 15,000 survivors of various childhood malignancies indicated that there was no significantly increased risk of non-hereditary cancer in their offspring.
Source: Sankila R, et al. Risk of cancer among offspring of childhood cancer survivors. N Engl J Med 1998;338: 1339-1344.
Sankila and associates from five nordic countries (Denmark, Finland, Iceland, Norway, and Sweden) assessed the incidence of cancer in the offspring of a large group of children who had cancer in childhood and adolescence and had survived into adult life. The health system of these countries permits almost complete ascertainment. A total of 14,652 childhood cancer survivors had 5847 offspring who were followed for 86,780 years for the development of cancer. A total of 44 malignancies occurred in the offspring group; 17 of these were retinoblastoma, which is often inherited. Five other cancers occurred in families with other hereditary cancer syndromes (Li-Fraumeni syndrome, neurofibromatosis, von Hipple-Lindu disease, etc.). There were a total of 22 cases of sporadic, non-genetic cancer compared to an expected incidence in the general population of 16.5 cases, a standardized incidence ratio of 1.3 (95% confidence levels), (0.8 - 2.0). This is a non-significant difference. Sankila et al conclude that there is no evidence of a significantly increased risk of non-hereditary cancer among the offspring of survivors of cancer in childhood.
COMMENT BY HOWARD A. PEARSON, MD, FAAP
The survival rate from childhood cancer has greatly increased over the past three decades. Sankila et al describe a 64-75% five-year across the board survival rate in Denmark and Finland, a percentage close to what is happening in the United States. Increasing numbers of survivors are entering the reproductive age group and are successfully having children of their own. Because of the rarity of childhood cancer, it has been difficult to estimate the risk of malignant neoplasms in the offspring of childhood cancer survivors or to reassure these patients.
This large collaborative study was able to assess this issue in a total population of about 20 million people during a 30-year period. The Nordic countries have nationwide cancer registries as well as a system for assigning unique personal identification numbers for all of their citizens. This enabled a computerized search for all offspring born to the 14,652 cancer survivors. The large sample size and the completeness of ascertainment and follow-up make the results of this study compelling, and overcomes the non-conclusiveness of earlier studies from the United States.1,2
The study shows that the risk of cancer among the children of childhood cancers (excluding retinoblastoma and other hereditary cancer syndromes) was small and did not differ significantly from the rest of the population. The study included all kinds of cancer. Although Sankila et al do not discuss the kinds of therapy these patients received, many of them probably received chemo and/or radiation therapy. Nearly half of the observed cancer in the offspring are known to be hereditary-especially retinoblastoma.
Sankila et al conclude with an optimistic recommendation to patients who have been cured of a wide range of non-hereditary childhood cancers: Fear of cancer in their offspring is no reason to discourage them from having their own children, and screening for cancer in offspring of the survivors of sporadic, non-hereditary cancers in childhood or adolescence is not warranted.