- The natural history of ACC can vary greatly with some patients surviving only months while others can live with disease for years. The basis for these differing clinical presentations is not known. While one cannot exclude an immune or other host component as responsible for the diverse clinical courses, it is also possible that there may be a genetic basis for this phenomenon. A bio-specimen repository will be a major step towards more comprehensive studies of this very rare and unusual tumor, and allow us to begin to characterize subgroups within the disease.