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Great strides have been made to improve outcomes for pediatric patients suffering from cancer, decreasing mortality by over 50% in the last half century. Despite these advancements in care, cancer remains a leading cause of mortality for children across the world. In the United States alone, approximately 15,800 children under age 20 are diagnosed with cancer annually, and nearly 2,000 are expected to die from the disease. Leukemia, lymphoma, and central nervous system tumors are the most common new cancer diagnoses in the pediatric age group. While many patients and families search for an explanation of why they have been afflicted by such a devastating illness, most pediatric cancers occur without known cause. Until recent years, a very small percentage of pediatric cancer was felt to be related to a genetic predisposition. With the advancement of modern techniques in molecular analysis, more cancer predisposition syndromes have been identified, and an estimated 10% of pediatric patients with cancer have a heritable cause. Early identification of these patients and initiation of cancer surveillance protocols is essential for reducing cancer-related mortality.1–4
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Heritable cancer predisposition syndromes in the pediatric population are a heterogenous group of disorders with a broad array of genotypic and phenotypic characteristics. In the simplest terms, a change in a child’s genetic makeup results in an imbalance in the system that regulates a cell’s ability to grow, differentiate, proliferate, and die. The mechanisms by which this imbalance and instability results in the development of malignancy can be used to characterize cancer predisposition syndromes into the following groups of defects: (1) DNA repair, (2) tumor suppressor genes, (3) proto-oncogenes, (4) transcription factors, (5) telomeres and RNA metabolism, (6) constitutional chromosomal abnormalities, and (7) primary immunodeficiency (Table 15.1).
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