Can we consider that epidrugs can constitute a good therapeutic strategy against cancer diseases?

Epidrugs can be used as drugs to treat cancer because many cancers develop due to abnormalities in epigenetic control of cell proliferation, growth, differentiations and death.
See Cancer Discov 2022;12:31–46 by Hanahan

The effectiveness of epidrugs may vary depending on the specific type of cancer and the individual patient.

why not? precision medicine will depend on this. 

In principal, epidrugs that modify DNA methylation or chromatin modification, or even utilize post-transcriptional mechanisms are promising venue to combat cancer. Problem is that targeting is difficult and requires more investigations. Second, I usually see cancer as a dedifferentiation rather than an uncontrolled proliferation phenomenon, albeit, such proliferation is an integral part of the dedifferentiation process. Therefore, a real success in our war against cancer needs treatment to go through the redifferentiation concept, rather than targeting proliferation and it's drivers as it kills individual cells, with huge off-target price, and not the root cause of the disease. 

Yes, we can consider epidrugs as a good therapeutic strategy against cancer diseases as they target the gene expression not the DNA sequence.

Phenotype is more important than genotype, and is regulate by external stimuli e.g., stess, food, exposure to xenobiotics and toxic agents etc. The best example for this are the identical twins (identical genotype) and as times passes by they diverge physically and in health status. Cancer is a  disease of the epigenome more than the genome since one can have mutations in important tumor supressor genes (e.g., BRAC1 and 2) but never develop cancer since at least one of those genes allels is normal. Alternatively, a person can have non-mutated tumor supressor genes and still develop cancer because those genes are note expressed as they are epigenetically silenced

Yes research warranted in the same