The Biology of Cancer - Vibrational Spectroscopy for Tissue Analysis - page 34

lymphomas , which account for approximately 7% of human malignancies,
arise from the blood-forming cells and from cells of the immune system,
respectively [7]. All cell types are susceptible but epithelial cells are most
prone to change. This means that most human malignancies arise from
epithelial tissue [5,6]. In fact, most human cancers (approximately 90%)
are carcinomas. This might be explained by two factors: cell proliferation
mainly occurs in epithelia, and they are more frequently exposed to vari-
ous forms of physical and chemical damage that favor the development
of cancer [8]. Dedifferentiation or anaplasia denotes the loss of normal
characteristics.
Epidemiology of Cancer
Epidemiology is the study of distribution and causes of disease in human
populations [5,9]. The epidemiological approach aims to provide an accu-
rate and representative picture of the pattern of cancer in the popula-
tion as a whole, and to help uncover the causes of cancer. The basis of
the epidemiological approach is simple. Information is collected in a rig-
orously standardized manner for every individual (or a representative
sample of individuals) diagnosed with or dying from cancer in a defined
population, and the resulting data set is analyzed with suitable statistical
techniques [9].
In developed countries, cancer is the second-biggest cause of death [10].
It has been proven that some factors can lead to an increased risk of cancer
development. For instance, lack of exercise [11], hypercholesterolemia [12],
increasing age [10], geographical differences, sex variations [13], ethnic
and racial differences, diet, smoking [14], and a family history of cancer
can have significant effects on the epidemiology and incidence of the
disease [5,9].
Although there are many kinds of cancer, only a few occur frequently.
Figure 3.1 [15] and Table 3.1 show the incidence and mortality rates of some
of the most common malignancies in the United Kingdom and the United
States. Cancer will afflict up to one in three persons before their seventy-
fifth birthday in developed countries, and one in four persons will die
from it [9].
More than one million cases of cancer are diagnosed annually in the
United States, and more than 500,000 Americans die of cancer each year.
Cancers of 11 different body sites account for more than 80% of this total
cancer incidence [7]. In the United Kingdom, almost a quarter of a million
cancers are diagnosed each year, and there are some 160,000 deaths [16].
Unfortunately, it has been shown that the number of cases that are diag-
nosed with cancer in the age group 55-84 is much higher in the United