A researcher conducting a study on the incidence of mutations to the MDR-1 gene in breast cancer has preliminary evidence of a link between mutated MDR-1 and early recurrence. The researcher begins a new trial using prospectively collected tissue samples to further examine the link between the genetic abnormality and disease progression. He believes that he may want to re-contact some or all of the tissue donors (subjects) if the research indicates a positive link between MDR-1 mutation and early disease recurrence. What is the best procedure for an investigator planning to re-contact study subjects who provided tumor tissue for the study?