On 2014 May 09, Madhusudana Girija Sanal commented:

It is all about numbers! It is statistics which defines what cancer is! One reason is that all definitions are a matter convenience for humans to classify, work or learn. Definitions quite often cannot be ‘black and white’ and hence statistical approaches are wise. The author note that the sixth hall mark of six hallmarks defined by Hannan and Weinberg, that is “the ability to invade and metastasis” is the only ‘real’ hallmark of cancer. However it is known that everything moves around, invade and proliferate need not be a cancer- example is endometriosis. Giant-cell tumor of the bone is considered benign but can spread to other parts including the lungs. Moreover during embryonic development different cell lineages compete and invade each other. Winners proliferate secrete autocrine factors, attracts blood vessels, force defeated cells to apoptosis or even ‘eat’ them up. This is not cancer! So what can be the hallmark or defining features of cancer? What I am proposing is a preliminary outline which may be further modified by “Wiki” efforts to make it more accurate. The following conditions needs to be satisfied to define a cancer: 1) Non physiological rate of cell division. Non physiological rate is defined as a growth rate which is a statistical outlier spatially and temporally for a given type of cell and organism. 2) A change, genetic or epigenetic with reference to the healthy genome which is a statistical outlier spatially and temporally for a given cell type and organism. Healthy reference genome and epigenome may be defined as the genome of individuals which satisfy two conditions a) falling within the statistically defined normal range of anatomical and physiological parameters for a population b) demonstrated longevity above 99.9 percentile of the population of a given organism.

Cancer is a dynamic process-continuous evolution and selection. It is often,but not mandatory (at least theoretically) to be started by or seeded by a mutation and 'nurtured' or maintained by epigenetics. This is because epigenetic modification are faster as well as reversible. The effect of environment is mediated often (through cytokines, microRNA or even by physical factors) through epigenetic adaptations.Sooner or later more mutations and epigenetic changes accumulate during evolution and selection. This process is accelerated by chemotherapy (especially when using alkylating agents) radiation. Very specific and interesting mutations can evolve during targeted therapy (example-nilotinib).

On 2014 May 09, Madhusudana Girija Sanal commented:

It is all about numbers! It is statistics which defines what cancer is! One reason is that all definitions are a matter convenience for humans to classify, work or learn. Definitions quite often cannot be ‘black and white’ and hence statistical approaches are wise. The author note that the sixth hall mark of six hallmarks defined by Hannan and Weinberg, that is “the ability to invade and metastasis” is the only ‘real’ hallmark of cancer. However it is known that everything moves around, invade and proliferate need not be a cancer- example is endometriosis. Giant-cell tumor of the bone is considered benign but can spread to other parts including the lungs. Moreover during embryonic development different cell lineages compete and invade each other. Winners proliferate secrete autocrine factors, attracts blood vessels, force defeated cells to apoptosis or even ‘eat’ them up. This is not cancer! So what can be the hallmark or defining features of cancer? What I am proposing is a preliminary outline which may be further modified by “Wiki” efforts to make it more accurate. The following conditions needs to be satisfied to define a cancer: 1) Non physiological rate of cell division. Non physiological rate is defined as a growth rate which is a statistical outlier spatially and temporally for a given type of cell and organism. 2) A change, genetic or epigenetic with reference to the healthy genome which is a statistical outlier spatially and temporally for a given cell type and organism. Healthy reference genome and epigenome may be defined as the genome of individuals which satisfy two conditions a) falling within the statistically defined normal range of anatomical and physiological parameters for a population b) demonstrated longevity above 99.9 percentile of the population of a given organism.

Cancer is a dynamic process-continuous evolution and selection. It is often,but not mandatory (at least theoretically) to be started by or seeded by a mutation and 'nurtured' or maintained by epigenetics. This is because epigenetic modification are faster as well as reversible. The effect of environment is mediated often (through cytokines, microRNA or even by physical factors) through epigenetic adaptations.Sooner or later more mutations and epigenetic changes accumulate during evolution and selection. This process is accelerated by chemotherapy (especially when using alkylating agents) radiation. Very specific and interesting mutations can evolve during targeted therapy (example-nilotinib).