The reasons for tumor dormancy can be many. These include; how many cells are in G0 phase, cell turnover equals cell death, lack of apocrine and paracrine signals or even endocrine stimulation, lack of angiogenesis, non-availability or masking of nutrients or oxygen supply, deficient ECM, hostile micro-environment, immunologic overpower and so on. Any factors, intrinsic or extrinsic, that overcome these hurdles or break the impasse, lead to awakening from dormancy. In fact, overt cancer growth is an outcome of constant host-cancer interactions, in which complex accumulation of genetic and epigenetic changes play their role.It is also known as multihit and multifactorial hypothesis, which is time and age dependent.