Chemistry Reference
In-Depth Information
growth is controlled by various cell cycle checkpoints and shows a normal growth
pattern. These cell cycle checkpoints are regulated by various genes and/or pro-
tein machinery. During development of cancer, various genes related to cell growth
become mutated, which leads to progression of the cancer phenotype. When cells
become cancerous, they start to divide in an uncontrollable manner and accumulate
in a particular area of the body. Uncontrolled dividing cells make lumps, which are
abnormal accumulations of cells and are called tumors/neoplasms. A tumor, or neo-
plasm, is an abnormal lump or mass of tissue that may compress, invade, and destroy
normal tissue. Tumors may be benign or malignant.
Based on the area affected, the names of different cancers vary. In colorec-
tal cancer, surface or epithelial cells become cancerous; thereby it is called ade-
noma. Colorectal cancer progresses through following stages: (1) early adenoma,
(2) intermediate, (3) late adenoma, (4) carcinoma, and (5) malignant or metastasis
(Figure 14.1).
1.
Early adenoma
: When normal gut epithelial cells are exposed with various altera-
tions in the genetic makeup and lose normal growth control, they start to multiply
uncontrollably. This stage of colorectal cancer is called early adenoma.
2.
Intermediate adenoma
: In this stage cancerous cells start to accumulate on the
surface area of the epithelial membrane and make abnormal aberrant crypt foci
(ACF), characterized by overconvolution in the gut surface.
3.
Late adenoma
: This is also a progressive step for overaccumulation of cancerous
cells, which makes other cells too sensitive and they also lose contact inhibition.
Up to this stage adenoma may be benign and may have a noncancerous phenotype,
if growth is suppressed at some point.
4.
Carcinoma
: In this phase, cancerous cells become overreactive and start to grow
very fast and produce an overgrown tumorlike structure. Cancerous cells start to
break the border between tissues and the circulatory system.
5.
Metastasis
: Circulatory system barriers are broken down in this stage, and cancer-
ous cells start to spread in the whole body via the circulatory system, that is, blood
and/or lymphatic system. These circulatory cancerous cells accumulate in other tis-
sues and make new tumors far away from the origin, and also invade other tissues.
14.3 ANTICArCINogENIC PoTENTIAl oF
ProbIoTICs AND PrEbIoTICs
The increasing prevalence of human colorectal cancer is receiving the atten-
tion of health professionals and researchers who seek better therapeutic and pre-
vention strategies. Although early detection and surgery have significantly reduced
both mortality or morbidity in patients affected by colorectal cancer, survival after
surgical treatment for advanced colorectal cancer, even if is followed by a number of
adjuvant therapies, has not seen significant improvement in recent years. Hence, pre-
vention of the development of colorectal cancer appears to be the more rational and
effective strategy. The multistep nature of colorectal cancer together with the con-
cept of carcinogenesis, that is, the phenomenon by which independent premalignant
