What happen when a virus infects a cancer cell?

What happen when a virus infects a cancer cell?
Depends. There are a number of different scenario dependent on the type of virus (the genetic payload).
Some scenarios:
1. Most promising it will kill the cancer cell much close to a normal cell. The virus will incorporate its DNA into the cell DNA and use it to produce more virus. Then, lysis of the cell which releases more viruses.
2. Some virus use a dormant lytic strategy using the cell but not killing it to propagate more virus. I suspect this would not effect either the cancer or the virus.
3. A few virus have be known to take oncogenes. These are incorporated into the cell genome and may add to the de-differentiation of the cell.
An interesting paddock of research is using viruses near engineered payloads to fight cancer. This is done by inserting manipulate genes inside a hollowed out virus vector such as the adenovirus. The new gene hopefully will "fix" the problem. Good contained by theory but, in that are difficulties such as delivering the gene to the right place within the genome (otherwise may cause more problems), deliver gene may be recessive, etc. This does not even mention the difficulties in identify "bad" genes and engineering "good" genes or the immune response. Gene therapy is still along instrument from being comprehensive used as a cancer therapy.
Well, since a virus shanghais a cell DNA to cause it to replicate the compulsory viral proteins to reproduce itself, and incongruities in the DNA are what cause cancer...
I would suspect that a cancer cell would be immune, or indifferent to a normal, human infecting virus...But possibly the altered DNA could be vulnerable to a gengineered virus that would be inept to affect normal sound cells...
Might be worth a shot...