Molecular epidemiology study of a suspected community cluster of childhood cancers.

We investigated the report of a community cluster of cancers in 33 children, which included two siblings known to have dominantly inherited Li-Fraumeni syndrome and a germline p53 mutation. After defining criteria for inclusion in the cluster, the 12 eligible childhood cancer probands diagnosed between 1980 and 1989 were not excessive (expected, ten cases). The corresponding childhood cancer mortality rates for the community fluctuated between 1950 and 1989 and were not increased overall. However, three additional probands had family histories of childhood cancer that suggested a forme fruste of Li-Fraumeni syndrome. The epidemiological data suggested a geographic cluster of this rare hereditary disorder, but absence of germline p53 mutation in the three other multicase families indicates genetic heterogeneity. Laboratory studies can assist analyses of suspected clusters, although investigations of geographic clusters of hereditary cancers raise complex issues of confidentiality and protection of affected individuals, their families, and the community.

Follow-up study of twenty-four families with Li-Fraumeni syndrome.

The Li-Fraumeni cancer family syndrome is manifested by susceptibility to breast cancer, sarcomas, and other neoplasms in children and young adults. The present study utilized clinical follow-up data on 545 members of 24 Li-Fraumeni kindreds living and cancer-free at family ascertainment. Two hypotheses were tested based on a model of autosomal dominant genetic predisposition: (a) that syndrome cancers would continue to occur excessively during follow-up compared to the general population, and (b) that the tumors would occur primarily among those family members likely to carry the gene. Population cancer rates were compared with cancer rates in follow-up of the cohort from ascertainment to 1988. Risk of carrying the gene for the syndrome at the time of ascertainment was calculated for each family member under two models with somewhat different definitions of affection with the syndrome. Cancer occurrence after ascertainment was then analyzed according to the risks. Cancer did continue to occur excessively among the entire cohort during follow-up [relative risk (RR 2.1)]. The excess was greatest below age 20 (RR 21.1), declined with increasing age, and was most pronounced for neoplasms featured in the syndrome (RR 18.2). Among persons less than age 45, at least 87% of cancers occurred in those at higher risk of carrying the gene under both genetic models (RR 22.9 and 21.3). The clinical data, therefore, reliably identify individuals likely to carry a dominantly inherited gene conferring susceptibility to a specific constellation of neoplasms. Recent identification of a germ line mutation in the tumor suppressor gene p53 in persons with the syndrome may, if confirmed, have implications for ultimately defining the component tumors of the syndrome and for the causes and prevention of those tumors arising outside these families.

A cancer family syndrome in twenty-four kindreds.

A search of the Cancer Family Registry of the National Cancer Institute revealed 24 kindreds with the syndrome of sarcoma, breast carcinoma, and other neoplasms in young patients. Cancer developed in an autosomal dominant pattern in 151 blood relatives, 119 (79%) of whom were affected before 45 years of age. These young patients had a total of 50 bone and soft tissue sarcomas of diverse histological subtypes and 28 breast cancers. Additional features of the syndrome included an excess of brain tumors (14 cases), leukemia (9 cases), and adrenocortical carcinoma (4 cases) before age 45 years. These neoplasms also accounted for 73% of the multiple primary cancers occurring in 15 family members. Six of these patients had second cancers linked to radiotherapy. The diversity of tumor types in this syndrome suggests pathogenetic mechanisms which differ from hereditary cancers arising in single organs or tissues. The syndrome is presently diagnosed on clinical grounds; laboratory markers are needed to identify high-risk individuals and families and to provide insights into susceptibility mechanisms that may be shared by a wide variety of cancers.