Amongst, the modifiable risk factors, tobacco leads the march, accounting for nearly 21 % of all cancers. Surprisingly, consumption of alcohol and inadequate intake of fruits and vegetables stand second and third respectively as causative factor of cancers.
Overweight and obesity, physical inactivity, unsafe sexual practices, air pollution due to the growing industrialization/ urbanization, smoke from domestic use of coal and contaminated health-care injections are the other preventable factors in the worldwide incidence of cancer.
Nearly 2.43 million of the 7 million cancer deaths that occurred worldwide in 2001 were due to these nine factors. Furthermore, 760,000 deaths occurred in high-income countries, while 1.67 million took place in low- and middle-income regions.
The significance of each of the preventable factors varies across different countries and cultures. For example, the indoor smoke arising out of charcoal would be very important in a country like India while overweight and lack of exercise may be vital in the United States. It should always be borne in mind that though the study point to risk factors in general; the individual risk assessment has to be subjective.
Amongst the described causes, smoking, alcohol and obesity were important in high-income countries while smoking; alcohol and low intake of fruits and vegetables were significant in low-income countries. Extreme caution has been excised in the estimation of these projected factors. Cancers that were known to be definitively related to the above-mentioned risk factors were excluded from the observation.
One of the merits of the present study is that a majority of the factors (Smoking, alcoholism, dietary intake of fruits and vegetables, obesity, physical inactivity, unsafe sex, indoor smoke) can be taken care of by the individual itself rather than Government or Health Organizations.
Although there has been an improved understanding of cancer biology in the recent years, cancer prevention would remain a sensible as the effectiveness of cancer treatment is still controversial.