1979-07 to 1980-06 | Intern in Medicine, New York University-Bellevue Hospital
1980-07 to 1981-06 | Junior Assistant Resident, New York University-Bellevue Hospital
1981-07 to 1982-06 | Senior Assistant Resident, Internal Medicine, New York University-Bellevue Hospital
1982-07 to 1983-06 | Chief Resident in Medicine, New York University-Bellevue Hospital
1983-07 to 1986-06 | Research Fellow, Laboratory of Molecular Hematology, National Institutes of Health
1986-07 to 1987-06 | Senior Staff Fellow, Laboratory of Molecular Hematology, National Institutes of Health
1987-07 to 1988-06 | Clinical Fellow in Medicine, Brigham and Women's Hospital
1987-07 to 1988-06 | Clinical Fellow in Medicine, Harvard Medical School
1987-07 to 1989-06 | Fellow in Medical Oncology, Dana Farber Cancer Institute
1988-07 to 1989-06 | Clinical Associate, Dana Farber Cancer Institute
1990-07 to 1992-06 | Assistant Physician, Dana Farber Cancer Institute
1990-07 to 1992-06 | Assistant Physician, Dana Farber Cancer Institute
1990-07 to 1997-06 | Assistant Professor of Medicine, Dana Farber Cancer Institute
1997-01 to 1999-12 | Founding Member, New England Coalition for Cancer Survivorship
1990-07 to 2004-06 | Associate Physician, Brigham and Women’s Hospital
1997-07 to 2004-06 | Associate Professor of Medicine, Brigham and Women's Hospital
1997-07 to 2004-06 | Associate Professor of Medicine, Dana Farber Cancer Institute
1997-07 to 2004-06 | Associate Professor of Medicine, Massachusetts General Hospital
2004-07 to 2015-07 | Professor of Medicine, Brigham and Women's Hospital
2004-07 to 2015-07 | Senior Physician, Brigham and Women's Hospital
2004-07 to 2015-07 | Physician, Brigham and Women's Hospital
2004-07 to 2015-07 | Professor of Medicine, Dana Farber Cancer Institute
2015-11 to present | Chairman of Medicine, Attending Physician (Memorial Hospital for Cancer and Allied Diseases, Department of Medicine )Memorial Sloan-Kettering Cancer Center