Genetic factors have lately become a focus of attention owing to the identification of specific cancer-associated genes (e.g., for breast cancer). It is estimated that a genetic predisposition accounts for about 5% of cancer morbidity. Some authors state a range of 5%-10% (e.g., Lynch et al. 1995). It has been established that genetic factors are involved in malignant neoplasms of the eye, bowel, breast, and ovaries.