Cancer is a disease characterized by genomic mutation, modified gene expression, cell proliferation, and aberrant cell growth. It ranks as one of the leading causes of death in the world. In the United States, cancer ranks as the second leading cause of death, with over 1.68 million new cases of cancer diagnosed and more than 0.6 million Americans dying from cancer annually (Siegel et al., 2016). Multiple causes of cancer have been established including infectious agents, radiation, and chemicals. Estimates suggest that 70% to 90% of all human cancers have a linkage to environmental, dietary, and behavioral factors (Fig. 8-1). Although our understanding of the biology of the progression from a normal cell to a malignant one has advanced considerably in the past several decades, many aspects of the cause, prevention, and treatment of human cancer and in particular the influence of lifestyle remain to be completely resolved.
Proportions of human cancer deaths attributed to various factors. (Reproduced with permission from [no authors listed] Harvard reports on cancer prevention: causes of human cancer. Center for Cancer Prevention Harvard School of Public Health. Cancer Causes and Control. 1996;7 (Suppl 1):S3–S4, 1996.)
An understanding of the cellular and molecular aspects of the cancer process requires an understanding of the scientific terms involved in defining and describing the pathology of neoplasia (Table 8-1). Neoplasia is defined as new growth or autonomous growth of tissue. A neoplastic lesion is referred to as a neoplasm. A neoplasm can be either benign or malignant. Both types of lesions are induced by chemical carcinogens. Benign neoplasms (e.g., adenomas) are lesions characterized by expansive growth, frequently exhibiting slow rates of proliferation that do not invade surrounding tissue or other organs. Benign neoplasms can impair and damage the normal function of an organ through its growth by impeding blood flow. A malignant neoplasm (e.g., a carcinoma) demonstrates invasive growth characteristics, capable of spreading not only through the organ of origin but also via metastasis to other organs. Metastases are secondary growths derived from the cells of the primary malignant neoplasm.
Table 8-1Terminology ||Download (.pdf) Table 8-1 Terminology
|Neoplasia ||New growth or autonomous growth of tissue |
|Neoplasm ||The lesion resulting from the neoplasia |
| Benign ||Lesions characterized by expansive growth, frequently exhibiting slow rates of proliferation that do not invade surrounding tissues |
| Malignant ||Lesions demonstrating invasive growth, capable of metastases to other tissues and organs |
|Metastases ||Secondary growths derived from a primary malignant neoplasm |
|Tumor ||Lesion characterized by swelling or increase in size, may or may not be neoplastic |
|Cancer ||Malignant neoplasm |
|Carcinogen ||A physical or chemical agent that causes or induces neoplasia |
| Genotoxic ||Carcinogens that interact with DNA resulting in mutation |
| Non-genotoxic ||Carcinogens that modify gene expression but do not damage ...|