In the last two decades, pioneering research fuelled by exponential growth in high-throughput technologies, has shed insights on several cancer causative factors in human environment, thereby making multiple forms of cancer preventable. There is a noticeable upward trend of research activities in direction of enhancing diverse combative cancer preventive strategies for high-risk population. Chemoprevention or chemo-protection can be defined as “the use of specific diets, or natural or synthetic chemicals, to reverse, suppress or prevent carcinogenic progression to invasive cancer”. The principal prevention strategy for cancer is to minimize the exposure of environmental carcinogens to risk population. However, many of the environmental factors responsible for initiating cancer still remains to be identified. Avoidance of already identified (suppose air pollution) factors demands alteration in life-style behavior, implementing which is not a feasible option .In recent times, lot of epidemiological studies are indicating that cancer is preventable by intervention with dietary changes. The conclusion of such studies are based on many causative factors such as, time trends in cancer incidence and mortality, variations in geographical locations and migration effect, lack of simple patterns of genetic inheritance for the majority of human cancers.
The Initiation step of carcinogenesis is a rapid process and in this process there is a direct involvement of carcinogen-binding and consequential damage to DNA which results in an irreversible mutation. The Initiation step is followed by Promotion step in which “clonal expansion” of initiated cells is noticeable. This feature is a result of induction of initiated cells by mutagenic agents. This stage of carcinogenesis can theoretically be reversed. The Progression stage of carcinogenesis is an expansion of the promotional stage. In this stage the cell there is a further proliferation of the cellular damage process induced by the promoters in the progression stage. During the process of tumour progression there is a gradual emergence of multiple genotypically and phenotypically altered cells. The promotion and progression phases of carcinogenesis is extended time-driven affair. Based on the phase of carcinogenesis, the chemopreventive agents show influence, the chemopreventive compounds can be broadly classified into two categories:
(i) Tumour 'blocking agents': The chemopreventive agents working against the progression cancer by interfering with the initiation step of carcinogenesis
(ii)Tumour 'suppressors: The chemopreventive agents working against the development cancer by interfering with the promotion or progression steps of carcinogenesis
A significant contribution of the “Blocking agents” is reduction of the accumulated mutations....