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FOUNDATION OVERVIEW

Modern medical science has led to significant improvement in survival and quality of life for individuals with neoplastic (neoplasm) conditions. Neoplasm (tumor or cancer) is an abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of normal tissues and persists after cessation of the stimuli which evoked the change. The key feature of cancer is unregulated cell division and growth, secondary to the loss of normal control mechanisms that govern cell survival, proliferation, and differentiation. Benign tumors are limited to the tissue of origin and do not invade surrounding tissue. Their dangerous counterpart, malignant tumors can invade local tissues and undergo distant spread (metastasis). Malignant tumors (often referred to as cancer) are predominantly of two types, solid tumors and hematologic malignancies. Solid tumors include various types of cancer, typically arising from a specific organ or site. They are characterized by their initial location as well as their cell of origin, including carcinomas (of epithelial origin) and the sarcomas (of connective tissue origin, mesenchymal origin). Hematologic malignancies include cancers that arise from cells in the hematopoietic cascade and are most commonly categorized as leukemias, lymphomas, or myeloma.

The impact of a particular cancer on a population can be assessed by calculating the lifetime risk of developing that cancer, the median age at diagnosis, and 5-year probability of survival after diagnosis (Table 10-1). The 5-year probability of survival for an individual with prostate cancer is nearly 100%, while the 5-year survival probability for pancreatic cancer and lung cancers are 9.1% and 18.7%, respectively. Several internal (eg, genetic predisposition, race, sex) and external (eg, environmental exposures like ionizing radiation, chemical carcinogens, viral infections) factors have been implicated as the cause of various types of cancer and are beyond the scope of this chapter. Screening can be used to detect cancer at an earlier, more treatable stage. Current recommendations for cancer screening are summarized in Table 10-2.

TABLE 10-1Top 10 United States Invasive Cancer Statistics

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