John Siebel, M.D.
NPI 1780741306 · Medical Oncology Physician · San Mateo, CA
Enrolled with Medicare as Practitioner - Medical Oncology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
John Siebel, M.D. is a Medical Oncology Physician provider in San Mateo, CA (NPI 1780741306).
Provider details
- NPI number
- 1780741306
- Entity type
- Individual
- Primary specialty
- Medical Oncology PhysicianAllopathic & Osteopathic Physicians
- Credential
- M.D.
- Sex
- Male
- Sole proprietor
- No
- License
- G26383 (CA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure38% of score
19 yrs in NPPES registry
- Profile completeness38% of score
100% of core fields populated
- Practice footprint23% of score
2 documented practice locations
Signals a provider has no public data for (e.g. Medicare claims) are left out of the score entirely — never counted as zero — so providers without that data are not penalized. See the full formula and weights in our methodology.
Practice location
Mailing address
Additional practice locations (1)
- 1250 Idaho StLewiston, ID 83501-1965Phone: (208) 743-7427Fax: (208) 743-7421
Registry dates
- Enumerated
- 2007-01-02
- Last updated
- 2018-11-07
Frequently asked questions
- What is John Siebel's NPI number?
- John Siebel's National Provider Identifier (NPI) is 1780741306, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is John Siebel's specialty?
- John Siebel is listed in the NPPES registry with a primary specialty of Medical Oncology Physician (Allopathic & Osteopathic Physicians).
- Where is John Siebel located?
- John Siebel's practice location on file with NPPES is 218 De Anza Blvd, San Mateo, CA 94402-3913.
- What is John Siebel's phone number?
- The practice phone number listed in the NPPES registry for John Siebel is (650) 341-9131.
- Does John Siebel accept Medicare?
- John Siebel is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is John Siebel's NPI active?
- Yes — John Siebel's NPI (1780741306) is active in the NPPES registry as of the last update on 2018-11-07.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.