Division of Cancer Epidemiology & Genetics, National Cancer Institute, Rockville, Maryland

Supported by the Intramural Research Program of the National Institutes of Health and the National Cancer Institute (#Z01 CP010124-21).

The authors declare that they have nothing to disclose.

Correspondence: Megan A. Clarke, PhD, MHS, Clinical Epidemiology Unit, Clinical Genetics Branch, Division of Cancer Epidemiology & Genetics, National Cancer Institute, 9609 Medical Center Drive, Room 6E536, Rockville, MD. E-mail: [email protected]