Ross S Berkowitz1, Donald Peter Goldstein2. 1. New England Trophoblastic Disease Center, Donald P. Goldstein Trophoblastic Tumor Registry, Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Dana Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA. Electronic address: rberkowitz@partners.org. 2. New England Trophoblastic Disease Center, Donald P. Goldstein Trophoblastic Tumor Registry, Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Dana Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.