Cancer is a leading cause of death worldwide. There are a lot of cancer causing agents which are divided as physical carcinogens, chemical carcinogens and biological carcinogens. But most of the carcinogens or causes of cancer are related to our lifestyle like diet, habit, occupation, radiation and some infection, etc. Chemoprevention is highly necessary to prevent cancer related preterm death. For this besides avoiding the causes of cancer we should concentrate ourselves on our diet. Because, numerous phytochemicals derived from edible plants have been reported to interfere with a specific stage of the carcinogenic process. Many mechanisms have been shown to account for the anticarcinogenic actions of dietary constituents and recently attention has been focused on intracellular-signalling cascades as common molecular targets for various chemopreventive phytochemicals. In this study, we tried to describe lifestyle related causes of cancer and the molecular basis of cancer prevention through the phytochemicals.