Quick answers
- Which hospitals does Jason A. Efstathiou work at?
- Medicare's official clinician data lists Jason A. Efstathiou at 5 hospitals: Brigham and Women's Hospital, Massachusetts Eye and Ear Infirmary -, Massachusetts General Hospital, Newton-Wellesley Hospital and North Shore Medical Center -. This is where the clinician works or has privileges; call the hospital to confirm.
- Where does Jason A. Efstathiou see patients?
- Medicare's clinician data lists 1 practice location in Boston, MA. Call before your visit to confirm the address.
- What is Jason A. Efstathiou's specialty?
- Medicare lists Radiation Oncology as the primary specialty.
- Does Jason A. Efstathiou accept Medicare assignment?
- Yes. Medicare's clinician data says Jason A. Efstathiou accepts Medicare assignment (the Medicare-approved amount as full payment for covered services), as of 2026-10-02. Ask the office to confirm before your visit.
- Does Jason A. Efstathiou offer telehealth?
- Medicare's clinician data says Jason A. Efstathiou offers telehealth services. Ask the office which visits can be done by video or phone.
- What is the phone number for Jason A. Efstathiou?
- (617) 726-2000, as listed in official Medicare / NPI Registry data.
- What is Jason A. Efstathiou's NPI number?
- 1598967523. The NPI (National Provider Identifier) is the clinician's permanent federal ID; you can look it up in the official NPI Registry.
Hospitals where Jason A. Efstathiou works
Medicare's Facility Affiliation Data lists Jason A. Efstathiou at these hospitals (updated 2026-10-02). Each hospital page shows its address, phone, emergency services, Medicare rating and all its clinicians.
- Brigham and Women's HospitalBoston, MA · Acute Care Hospital · CCN 220110
- Massachusetts Eye and Ear Infirmary -Boston, MA · Acute Care Hospital · CCN 220075
- Massachusetts General HospitalBoston, MA · Acute Care Hospital · CCN 220071
- Newton-Wellesley HospitalNewton, MA · Acute Care Hospital · CCN 220101
- North Shore Medical Center -Salem, MA · Acute Care Hospital · CCN 220035
Practice locations
Addresses where Jason A. Efstathiou is enrolled with Medicare (CMS data updated 2026-10-02).
- 55 Fruit StBoston, MA 02114 (617) 726‑2000
Group practices
Medicare enrollment lists Jason A. Efstathiou as a member of these groups (CMS data updated 2026-10-02).
- Massachusetts General Physicians Organization Inc3,558 clinicians in the group
- The General Hospital Corporation1,267 clinicians in the group
Specialties
- Radiation Oncologyprimary
Other radiation oncologists in Boston
Clinicians with the same Medicare primary specialty in Boston, MA — not a recommendation.
Clinician information
| Medical school | Harvard Medical School |
|---|---|
| Graduation year | 2003 |
| Gender (as listed) | Male |
| Medicare assignment | Accepts (Medicare-approved amount as full payment) |
| Telehealth | Offers telehealth services |
| NPI (National Provider Identifier) | 1598967523 |
| Corrections | Report an error or suggest an update → |
Most corrections must be made at the source: clinicians update their NPI Registry record (NPPES) and their Medicare enrollment (PECOS); this page follows the next data release.
Sources
- Facility Affiliation Data — Centers for Medicare & Medicaid Services (CMS), data updated 2026-10-02, retrieved 2026-10-29
- National Downloadable File (Doctors and Clinicians) — CMS, data updated 2026-10-02, retrieved 2026-10-29
- NPI Registry — U.S. Department of Health and Human Services (NPPES), the clinician’s official record
- Medicare Care Compare — official Medicare tool to look up clinicians