186
8.1
Introduction
Carcinogenesis is the conversion of normal cells to cancerous cells through many
stages, which happen over many years or even decades. In the initiation stage of
carcinogenesis the carcinogens react with the DNA of the cells, and blocking this
stage (onset) of cancer is an important approach in cancer prevention or treatment.
Promotion, the second stage of cancer, may arise slowly over a long period of time,
ranging from several months to years. The third stage is the progressive stage,
involving the spread of the cancer. During the initiation and promotion stages of
cancer, a change in lifestyle and diet could possibly prevent development of cancer.
During the progressive stage, protective factors such as diet or lifestyle do not have
much impact (Reddy et al. 2003). Garlic, ginger, soya, curcumin, onion, tomatoes,
cruciferous vegetables, chillies, and green tea provide protection against cancer.
According to the International Agency for Research on Cancer (IARC), in 2012
“there were 14.1 million new cancer cases, 8.2 million cancer deaths and 32.6 million people living with cancer (within 5 years of diagnosis) worldwide. 57% (8
million) of new cancer cases, 65% (5.3 million) of the cancer deaths and 48% (15.6
million) of the 5-year prevalent cancer cases occurred in the less developed regions.
In India, 1.02 million new cancer cases, 0.7 million cancer deaths and 1.8 million
people living with cancer (within 5 years of diagnosis) in 2012” (http://globocan.
iarc.fr/Pages/fact_sheets_cancer.aspx).
In spite of the amount of money in billions being spent on cancer research and
the availability of the best health care in the world, there is high incidence of cancer
in the United States. Lifestyle seems to be one major contributing factor to cancer,
evident from the high incidence of cancer among immigrants from the East to the
West (Kolonel et al. 2004a).
Carcinogenesis begins with cellular transformation, progresses to hyperproliferation and inflammatory processes, and finally leads to angiogenesis and
metastasis. It is a three-phase process, which includes initiation, promotion, and
progression of the tumour (Berenblum 1982). Oxidative damage to DNA, proteins,
and lipids, resulting from an increase in oxidative stress, is considered to be one of
the most important mechanisms contributing to the development of cancer. Since
cancer is a multi-step process, the preventative action of phytochemicals may result
from their additive or synergistic effects. A number of mechanisms exist by which
phytochemicals aid in the prevention of cancer and they may include:
(i) Anti-oxidant and free radical scavenging activity
(ii) Induction of apoptosis
(iii) Anti-proliferative activity
(iv) Cell-cycle arresting activity
(v) Enzyme inhibition
(vi) Gene regulation (Liu 2004)
The search for potential anti-cancer agents from natural products dates back to
1550 BC. Scientific research reports only started emerging in the 1960s, with
A. Augustine and G.S. Pillai
8.1
Introduction
Carcinogenesis is the conversion of normal cells to cancerous cells through many
stages, which happen over many years or even decades. In the initiation stage of
carcinogenesis the carcinogens react with the DNA of the cells, and blocking this
stage (onset) of cancer is an important approach in cancer prevention or treatment.
Promotion, the second stage of cancer, may arise slowly over a long period of time,
ranging from several months to years. The third stage is the progressive stage,
involving the spread of the cancer. During the initiation and promotion stages of
cancer, a change in lifestyle and diet could possibly prevent development of cancer.
During the progressive stage, protective factors such as diet or lifestyle do not have
much impact (Reddy et al. 2003). Garlic, ginger, soya, curcumin, onion, tomatoes,
cruciferous vegetables, chillies, and green tea provide protection against cancer.
According to the International Agency for Research on Cancer (IARC), in 2012
“there were 14.1 million new cancer cases, 8.2 million cancer deaths and 32.6 million people living with cancer (within 5 years of diagnosis) worldwide. 57% (8
million) of new cancer cases, 65% (5.3 million) of the cancer deaths and 48% (15.6
million) of the 5-year prevalent cancer cases occurred in the less developed regions.
In India, 1.02 million new cancer cases, 0.7 million cancer deaths and 1.8 million
people living with cancer (within 5 years of diagnosis) in 2012” (http://globocan.
iarc.fr/Pages/fact_sheets_cancer.aspx).
In spite of the amount of money in billions being spent on cancer research and
the availability of the best health care in the world, there is high incidence of cancer
in the United States. Lifestyle seems to be one major contributing factor to cancer,
evident from the high incidence of cancer among immigrants from the East to the
West (Kolonel et al. 2004a).
Carcinogenesis begins with cellular transformation, progresses to hyperproliferation and inflammatory processes, and finally leads to angiogenesis and
metastasis. It is a three-phase process, which includes initiation, promotion, and
progression of the tumour (Berenblum 1982). Oxidative damage to DNA, proteins,
and lipids, resulting from an increase in oxidative stress, is considered to be one of
the most important mechanisms contributing to the development of cancer. Since
cancer is a multi-step process, the preventative action of phytochemicals may result
from their additive or synergistic effects. A number of mechanisms exist by which
phytochemicals aid in the prevention of cancer and they may include:
(i) Anti-oxidant and free radical scavenging activity
(ii) Induction of apoptosis
(iii) Anti-proliferative activity
(iv) Cell-cycle arresting activity
(v) Enzyme inhibition
(vi) Gene regulation (Liu 2004)
The search for potential anti-cancer agents from natural products dates back to
1550 BC. Scientific research reports only started emerging in the 1960s, with
A. Augustine and G.S. Pillai