The Biology of Cancer - Vibrational Spectroscopy for Tissue Analysis - page 33

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The Biology of Cancer
To understand chemical structural properties of cancer and associated
changes with the progression of disease, it is important to understand
the biology and chemistry of cancer. The term neoplasia , which literally
means new growth , is used clinically to describe pathologic tissue masses,
which grow independent of and faster than normal tissues. Most of the
body cells repair and reproduce themselves similarly in spite of their dif-
ferent functioning and appearance. As long as this process takes place in
an orderly manner, everything is under control. However, when it gets out
of control, a lump, called a tumour , develops. A neoplasm (tumour) may be
classified as in situ, benign, or malignant, based on its potential to harm
the host body. Malignant tumours are also called cancers [1,2,3]. Benig n
tumours are not considered cancer. They do not threaten life because they
do not spread to other organs, and once they are removed, they rarely
reappear. In situ tumours look like cancer in their morphology. In gen-
eral, they develop in epithelium. These small tumours remain in the epi-
thelial layer. A malignant tumour consists of cancer cells that sometimes
spread away from the original (primary) cancer to other organs through
the lymphatic system and bloodstream causing damage to organs and tis-
sues near the tumour. When they get to another part of the body, they may
divide forming a new tumour called a secondary or a metastasis tumour [4].
A biopsy is used by doctors to decide whether a tumour is benign or can-
cerous in which a small sample of cells is examined under a microscope.
Uncontrolled growth is the core property of cancers, which were known
to the early Egyptians [3,5]. Hippocrates reportedly distinguished benign
from malignant tissues [6].
Although cancer has multiple causes and exceptions, an acceptable clini-
cal definition would be: a set of diseases characterized by unregulated cell
growth leading to invasion of surrounding tissues and spread ( metastasis ) to
other parts of the body. Invasion and metastasis distinguish cancers from
benign growths [5].
The nomenclature of a neoplasm reflects its microscopic origin as well as
the potential to harm the host. For example, cancers arising from glandular
epithelial tissues are called adenocarcinomas , where the suffix carcinoma indi-
cates the epithelial origin and the prefix adeno reflects the glandular origin.
On the other hand, cancers arising from the mesenchymal tissue are called
sarcomas [1,3]. Leiomyosarcoma (sarcoma of smooth muscle) and liposar-
coma (sarcoma of fat cells) are examples of this type [5]. Leukemias and
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