Cesar Castro, M.D., M.SC.
Cesar Castro, M.D., M.SC. is a Medical Oncology Physician in Boston, MA, registered under NPI 1184824112. This provider registers 2 separate taxonomy codes, which usually means they practise across more than one recognised specialty. NPPES records them as a sole proprietor, meaning the practice is not incorporated as a separate legal entity.
Getting there
The practice address on file is 185 CAMBRIDGE ST FL 5, Boston, MA 02114. We have not yet mapped what surrounds this office — parking, transit, and nearby pharmacies are added as our data collection reaches each location.
Credentials and Medicare
| Licence | State | Specialty |
|---|---|---|
| 235484 | MA | Medical Oncology Physician primary |
| 235484 | MA | Internal Medicine Physician |
This provider holds licence 235484 issued in MA. A licence number in NPPES reflects what was filed at registration — it does not confirm the licence is still active today.
- Status
- Approved
- Provider type
- Practitioner - Hematology/oncology
- PAC ID
- 0648448423
Enrolled in Medicare 2 times, across 2 states:
| State | Enrollment ID | Provider type |
|---|---|---|
| Massachusetts | I20110721000558 | Practitioner - Hematology/oncology |
| New Hampshire | I20130416000415 | Practitioner - Hematology/oncology |
Medicare enrolment is recorded as approved under the provider type Practitioner - Hematology/oncology. There are 2 separate enrolment records across 2 states (MA, NH). Multiple enrolments usually mean the provider bills Medicare from more than one practice location, or has kept an earlier enrolment after moving. Each record carries its own enrolment ID, listed above. Being enrolled means the provider can bill Medicare; it does not tell you whether they are currently accepting new Medicare patients. Call the office to confirm.
What Medical Oncology covers
An internist who specializes in the diagnosis and treatment of all types of cancer and other benign and malignant tumors. This specialist decides on and administers therapy for these malignancies as well as consults with surgeons and radiotherapists on other treatments for cancer. NUCC Health Care Provider Taxonomy, code 207RX0202X
All registered taxonomy codes
This provider registers 2 taxonomy codes. The primary code is what appears on most claims; the others record additional recognised specialties.
| Code | Specialty | Licence | State | |
|---|---|---|---|---|
| 207RX0202X | Medical Oncology Physician Medical Oncology | 235484 | MA | primary |
| 207R00000X | Internal Medicine Physician | 235484 | MA |
The taxonomy records how the provider classifies their own practice. It does not confirm which conditions they currently treat, whether they are accepting new patients, or which insurance they take — call the office for that.
Full NPPES record
An NPI-1 identifies a single person. It stays with the clinician for life, even if they move practice or change state, which is why the address on file can lag behind where they actually work today.
| NPI | 1184824112 valid check digit |
|---|---|
| Entity type | Individual (NPI-1) |
| Enumeration date | Jul 18, 2007 |
| Last updated | Feb 9, 2026 |
| Status | Active |
| Sole proprietor | Yes |
| Credential | M.D., M.SC. |
| Practice address |
185 CAMBRIDGE ST FL 5 Boston, MA 02114 (617) 726-2000 Fax (617) 643-3244 |
| Mailing address |
55 FRUIT ST Boston, MA 02114 |
Number check
How the check works, step by step
Every NPI carries a Luhn check digit — the same scheme used on credit cards. CMS prefixes the number with 80840 before computing it, which marks it as a US health identifier.
| Digit | 8 | 0 | 8 | 4 | 0 | 1 | 1 | 8 | 4 | 8 | 2 | 4 | 1 | 1 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Doubled? | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 | — | ×2 |
| Value | 8 | 0 | 8 | 8 | 0 | 2 | 1 | 7 | 4 | 7 | 2 | 8 | 1 | 2 |
Sum = 58 · next multiple of 10 = 60 · check digit = 2 · actual last digit = 2
A valid check digit only means the number is well-formed. It does not mean the provider is licensed, active, or in good standing — those are separate questions answered by the sections above.