Smart Nanocarriers Bearing Docetaxel for Improved Chemotherapy Cancer (ePub)

Cancer is a term used for a collection of diseases in which some of the normal and somatic body
cells start dividing and re-dividing out of control . It is a leading cause of the
morbidity and mortality worldwide, second only to the cardiovascular diseases . The occurrence of cancer is not new to human kind and the world's oldest recorded case of breast cancer dates back to 1500 BC from ancient Egypt. Some evidences of human osteosarcoma were
also found in mummies in ancient Egypt which have been recorded in the manuscripts
dated about 1600 B.C . The word cancer, however, was first used by a physician
Hippocrates which finds its origin in a Greek word 'karkinos' to describe carcinoma
tumors .

Our body is made up of the trillions of cells and any one of them could be the site of cancer
initiation. During the normal physiological course, the human cells grow and divide to form new
cells as and when the need arises (McDonald, Fielding, & Dedhar, 2008).
Simultaneously, the old and damaged cells die and new cells replace them. This process
operates in a checked manner. But this methodical operation breaks down when cancer
develops and cells grow in an unchecked manner. These abnormal cells then form solid
growths called tumors . Some cancers like that of blood cells and known as leukemias
do not form solid tumors and remain floating in the blood stream and may reach other distal
organs. The DNA damage repair, which is an inherent mechanism in normal cells, is
compromised in cancerous cells. This damaged DNA can often be inherited leading
to a genetic predisposition to cancer.

Cancer can be classified according to the organ of origin or according to the cells
of the origin of cancer . On the basis of the cells of origin, major types of clinically identified cancer are carcinomas, sarcomas,
leukaemias, lymphomas, myelomas, and brain and spinal cord cancer. Carcinomas are the most common
type of cancer begins in the skin or in epithelial cells which lines the external body surface and
covers the internal organs. These have been further classified into the subtypes such as,
transitional cell carcinoma, basal cell carcinoma, squamous cell
carcinoma and adenocarcinoma etc. depending upon the epithelial layer of origin .