Definition: uncontrolled growth of abnormal cells in the body
Pathophysiology: The term cancer refers to a malignant tumor; a tumor that grows rapidly, isn’t encapsulated, invades local structures and tissues, is poorly differentiated, has rapidly dividing cells, and can spread distantly through blood vessels and lymphatics. These malignant tumors are made of tissue that overgrows and is independent of the body’s governing systems. Cancers are termed according to the cell type from which they originate; those arising from epithelial tissue are called carcinomas, from ductal or glandular structures are adenocarcinomas, those from connective tissues have the suffix sarcoma, from lymphatic tissue are called lymphomas, and those from blood-forming cells are called leukemias. Others are from historical reasons such as Hodgkin disease and Ewing sarcoma. Normal cells are governed by the body systems and have limited life spans but eventually cease growing and dividing then die. Cancer cells are usually immortal, having an unlimited lifespan, constantly growing and dividing. Cancer cells experience anaplasia, the absence of differentiation, causing disorganization in size and shape, mutating them from the normal cells of the body. Cancer can grow rapidly or slowly, progressing from normal cell tissue to neoplasm. Cancer forms a sequence of cellular and tissue changes progressing from dysplasia to carcinoma in situ and then to invasive cancer. Presence of anaplastic cells and loss of normal tissue architecture signify the development of cancer. This progression is easily seen in the squamous epithelium. The high rate of cell division, local mutagens, and inflammatory mediators all contribute to the accumulation of genetic abnormalities that lead to cancer. The mutation of these cells can happen at a chromosomal or genetic level and once it happens it can continuously happen as that originally mutated cell divides (cancer stem cell), making other cells
References: American Cancer Society. (2013). Retrieved from http://www.cancer.org/ Dugdale, D. (2010). Retrieved from U.S. National Library of Medicine website: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002267/ McCance, K. L., Huether, S. E., et al, S. E., et al, S. E., & et al, S. E. (2010). Pathophysiology: The biologic basis for disease in adults and children. (6th ed.). Maryland Heights, Missouri: Mosby.