Yes, there is a definite connection between epigenetic modifications and cancer progression...A large no. epigenetic inhibitors (mostly Histone deacetylase inhibitors) are in different phases of clinical trials for their use in cancer therapy.

Undoubtedly, there is a very strong correlation between epigenetics and cancer causation as well as its progression. In fact, cancer development and cancer biology are extremely complex , much of which remains unknown. It is proven that cancer formation is the net result of accumulation of multiple genetic and epigenetic alterations or events, also called multi-hit theory of cancerogenesis. Genetic changes are those that affect genes directly, altering codon sequences or in other words mutations and that too mostly point mutations, the classical example of which is seen as ras mutations. The genes can also be altered through chromosomal rearrangement or translocations, resulting in formation of hybrid genes such as those of Burkitt's lymphoma or even by amplification observed commonly in myc. Epigenetics do not affect genes directly, but rather indirectly, by altering gene expression, which is tightly controlled by regulatory sequences upstream or downstream the genes proper i e promoter and enhancer sequences.The alterations in promoters and enhancers are brought about by methylation and histone modifications. All these genetic and epigenetic changes may merge and lead to dysregulation of complex and interlacing molecular mechanisms overlooking the cell growth, proliferation and differentiation pathways through activation of oncogenes, down-regulation or inhibition of anti-oncogenes, stimulating angiogenesis,decreasing apoptosis, inducing telomerases or making cells immortal, affecting DNA repair and by promoting invasion and metastasis. Thus uncontrolled cellular prolifiration, clonal expansion, heterogenity are accquired with the passage of time, resulting in a covert to overt neoplasia, further spreading to newer locations in the body, overthrowing bodily controls and overpowering body defences and finally becoming autonomous, in other words, the killer or cancer.

Cadmium also posses epigenic activity in developing cancer ....it does not involvement of gene in developing cancer...by inducing oxidative stress it may induce cancer

Although in low doses cadmium is not believed to cause cancer, but recent data suggests that at higher doses and because of its long half life, it may excessively damage DNA by free radical injury and more particularly the DNA repair system, as I pointed out above, to cause cancer. It also may stimulate pathological estrogen-like effects, thereby possibly instigating hormone dependent cancers such as those of the prostate and the breast.

http://www.nature.com/nature/journal/v471/n7339_supp/full/471S12a.html

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1480584

http://www.nejm.org/doi/full/10.1056/NEJMra072067

check these 2 artilces which I hope are going to answer your question

very interesting answers. I have been working on protein posttranslational modifications, I have a feeling that some of major human diseases are definitely linked to abnormal epigenetic regulations at the PTM level. But cancer is a very different type of disease and its mechanism is not that clear.

if we look at the sporadic breast cancer specially at BRCA1 gene the peomotor is hyper mythylated thats why it dose not express thus responsible for breast cancer. also expression of emryonic protein in some cancer as a molecular biomarker shows role of epigenetics in cancer.