chewing, and also duration of consumption. In India, the per capita consumption of
cigarettes has seen an increase by 2% over the last decade. Estimates for the annual
number of persons developing disease attributable to their tobacco habit in
mid-eighties included 1,08,000 annual incident cases of cancer (Brennan
and Boffetta 2004). The first report of an association between tobacco smoking
and lung cancer risk came in 1950 (Wynder and Graham 1950; Doll and Hill 1950)
and over the subsequent years, several studies not only confirmed this finding but
also found that tobacco smoking also increases the risk of several other neoplasms.
In 2004, International Agency for Research on Cancer (IARC) classified tobacco
smoking as carcinogenic to humans and gave evidence for the relationship between
cigarette consumption and cancers of several regions of body such as lung, head and
neck, stomach, pancreas, liver, kidney, ureter, urinary bladder, cervix, and leukemia.
In Indian context, a National survey revealed that smoking tobacco is more prevalent
in men while women chewed tobacco more and the regular consumption of tobacco
is more prevalent in later stages of life (50 years and more) in both men and women
(Neufeld et al. 2005). The recent National Cancer Registry Programme (NCRP) data
on Tobacco related cancers (TRC) analyzed in a study conducted by Asthana et al.
(2016) revealed that approximately one-fourth of all cancers among men and
one-fifth among women were tobacco related. The maximum incidence among
men was reported for esophagus, lungs, and hypopharynx cancers from the Northeast of India and mouth cancer for Western India. Among women, maximum rates
were reported for esophagus and lung cancers in the Northeast region. The overall
risk of developing TRC was highest in the Northeast region compared to all other
regions. A study which compared the overall incidence of all cancer cases from
Northeast region and other regions from India observed a higher cancer incidence in
the Northeast. The study also compared Northeast cancer incidence data with global
data and found its similarities with the Southeast Asian region. This might be due to
the similarities between the genetic pool of people in Northeast region of India and
Southeast Asian region (Sharma et al. 2014).
10.2.2 Alcohol and Cancer Risk
Alcohol has been known to be responsible for several health and social issues and is
responsible for about three million deaths each year with about 5.1% of the global
burden of disease and injury (World Health Organization 2018). Besides being a
causal factor for several health issues such as liver cirrhosis, epilepsy, poisoning,
etc., alcohol consumption was estimated to have caused around 500,000 cancer
deaths worldwide in 2004, 4.4% of cancer deaths in China in 2005 and 3.5% in the
USA in 2009. The first study demonstrating the carcinogenic effect of alcohol was
published in 1903 (Newsholme 1903) followed by several such studies which paved
the way for the International Agency for Research on Cancer (IARC) listing alcohol
among the carcinogens for oral cavity and pharynx, esophagus, liver, and larynx.
The list was updated to include two more sites colorectum and female breast in 2010
following the studies conducted by Hamajima et al. (2002) and Ferrari et al. (2007).
10 Interactions of Environmental Risk Factors and Genetic Variations: Association. . .
215
cigarettes has seen an increase by 2% over the last decade. Estimates for the annual
number of persons developing disease attributable to their tobacco habit in
mid-eighties included 1,08,000 annual incident cases of cancer (Brennan
and Boffetta 2004). The first report of an association between tobacco smoking
and lung cancer risk came in 1950 (Wynder and Graham 1950; Doll and Hill 1950)
and over the subsequent years, several studies not only confirmed this finding but
also found that tobacco smoking also increases the risk of several other neoplasms.
In 2004, International Agency for Research on Cancer (IARC) classified tobacco
smoking as carcinogenic to humans and gave evidence for the relationship between
cigarette consumption and cancers of several regions of body such as lung, head and
neck, stomach, pancreas, liver, kidney, ureter, urinary bladder, cervix, and leukemia.
In Indian context, a National survey revealed that smoking tobacco is more prevalent
in men while women chewed tobacco more and the regular consumption of tobacco
is more prevalent in later stages of life (50 years and more) in both men and women
(Neufeld et al. 2005). The recent National Cancer Registry Programme (NCRP) data
on Tobacco related cancers (TRC) analyzed in a study conducted by Asthana et al.
(2016) revealed that approximately one-fourth of all cancers among men and
one-fifth among women were tobacco related. The maximum incidence among
men was reported for esophagus, lungs, and hypopharynx cancers from the Northeast of India and mouth cancer for Western India. Among women, maximum rates
were reported for esophagus and lung cancers in the Northeast region. The overall
risk of developing TRC was highest in the Northeast region compared to all other
regions. A study which compared the overall incidence of all cancer cases from
Northeast region and other regions from India observed a higher cancer incidence in
the Northeast. The study also compared Northeast cancer incidence data with global
data and found its similarities with the Southeast Asian region. This might be due to
the similarities between the genetic pool of people in Northeast region of India and
Southeast Asian region (Sharma et al. 2014).
10.2.2 Alcohol and Cancer Risk
Alcohol has been known to be responsible for several health and social issues and is
responsible for about three million deaths each year with about 5.1% of the global
burden of disease and injury (World Health Organization 2018). Besides being a
causal factor for several health issues such as liver cirrhosis, epilepsy, poisoning,
etc., alcohol consumption was estimated to have caused around 500,000 cancer
deaths worldwide in 2004, 4.4% of cancer deaths in China in 2005 and 3.5% in the
USA in 2009. The first study demonstrating the carcinogenic effect of alcohol was
published in 1903 (Newsholme 1903) followed by several such studies which paved
the way for the International Agency for Research on Cancer (IARC) listing alcohol
among the carcinogens for oral cavity and pharynx, esophagus, liver, and larynx.
The list was updated to include two more sites colorectum and female breast in 2010
following the studies conducted by Hamajima et al. (2002) and Ferrari et al. (2007).
10 Interactions of Environmental Risk Factors and Genetic Variations: Association. . .
215