Why can immune system attack virally infected cells but not cancer cells? Normally both cells are self recognized.

Immune system normally attacks virally infected cells because of that infected cells present mhc1. But also, virally infected cells are the self recognized cells. so it has also "don't eat me" signal on it. Although they have "don't eat me" signal how can immune system response to mhc1 and eat virally infected cells? So, if virally infected self recognized cells can be eaten by immune system, why aren't cancer cells not eaten. I know that cancer cells are self recognized also and they have don't eat me signals too. So, why immune system don't destroy them like virally infected cells? Can you advise me some articles about how immune system attacks self recognized cells? Thanks. 

Edited March 2, 20205 yr by Loui