Abstract
Cancer control can be improved through the application of knowledge of the hereditary aspects of certain malignant and premalignant disorders. A concrete example of the effectiveness of the application of genetic knowledge has been demonstrated by study of a family wherein five of seven siblings manifested xeroderma pigmentosum. Knowledge of the hereditary aspects of this disorder and its discovery in one sibling led to the immediate detection of the disorder in other siblings. In turn, preventive measures were instituted toward the avoidance of exposure to the carcinogenic effects of sunlight. Genetic counseling alleviated anxiety and major misconceptions among the family members concerning the hereditary aspects of this disorder.