William Gwin, MD
NPI 1598875882 · Medical Oncology Physician · Seattle, WA
Enrolled with Medicare as Practitioner - Medical Oncology · source: CMS PECOS Public Provider Enrollment (2026.04.01)
William Gwin, MD is a Medical Oncology Physician provider in Seattle, WA (NPI 1598875882).
Provider details
- NPI number
- 1598875882
- Entity type
- Individual
- Primary specialty
- Medical Oncology PhysicianAllopathic & Osteopathic Physicians
- Credential
- MD
- Sex
- Male
- Sole proprietor
- No
- License
- MD60094874 (WA)
Specialties & taxonomies
Allopathic & Osteopathic Physicians
Profile Score
A profile completeness & documented-activity index — NOT a quality, outcomes, or patient-satisfaction rating.
- Registry tenure25% of score
19 yrs in NPPES registry
- Profile completeness25% of score
100% of core fields populated
- Practice footprint15% of score
1 documented practice location
- Medicare service volume (vs. specialty peers)25% of score
280 Medicare services, 2024 (ranked within specialty)
- Open Payments transparency10% of score
Has Open Payments disclosures (2024)
Medicare volume is ranked against active providers in the same specialty. 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 .
What this provider does (Medicare)
Based on Medicare fee-for-service claims, 2024; not all care is captured.
| Service (HCPCS) | Medicare services | Typical Medicare-allowed (2024) |
|---|---|---|
| Established Patient Office Or Other Outpatient Visit With High Level of Medical Decision Making, If Using Time, 40 Minutes Or More99215 | 172 | $158 |
| Visit Complexity Inherent to Evaluation and Management Associated With Medical Care Services That Serve As the Continuing Focal Point for All Needed Health Care Services And/Or With Medical Care Services That Are Part of Ongoing Care Related to a Patient'SG2211 | 58 | $18 |
| Established Patient Office Or Other Outpatient Visit With Moderate Level of Decision Making, If Using Time, 30 Minutes Or More99214 | 32 | $103 |
| New Patient Office Or Other Outpatient Visit With a High Level of Medical Decision Making, If Using Time, 60 Minutes Or More99205 | 18 | $199 |
Typical Medicare-allowed amounts for these services range $18–$199 (2024). The Medicare-allowed amount is what Medicare recognizes for a service under fee-for-service — a reference figure for 2024, not a price quote and not what you would be billed. Medicare Part B covers roughly an eighth of all NPIs (65+ skew); services with fewer than 11 beneficiaries are suppressed by CMS. Source: CMS Medicare Physician & Other Practitioners, by Provider & Service.
What this provider prescribes (Medicare Part D)
Top drugs by Medicare Part D claim volume, 2024 · 7 distinct drugs on file.
| Drug | Part D claims (2024) | Beneficiaries |
|---|---|---|
| Letrozole | 43 | 17 |
| Anastrozole | 19 | — |
| Tamoxifen Citrate | 18 | — |
| Ribociclib Succinatebrand: Kisqali | 15 | — |
| Palbociclibbrand: Ibrance | 14 | — |
| Ondansetron Hcl | 12 | — |
| Capivasertibbrand: Truqap | 12 | — |
Medicare Part D only. These counts cover prescriptions paid through Medicare Part D in 2024 — they include cash-pay, commercial-insurance, Medicaid, or Part B–administered drugs, and badly undercount high cash-pay categories (e.g. GLP-1 weight-loss, testosterone, and ED medications). Any drug with 10 or fewer claims is omitted by CMS, and beneficiary counts under 11 are suppressed — so a missing drug means , never zero. This is a factual claims summary, not an endorsement, not medical advice, and not a consumer report. Source: CMS Medicare Part D Prescribers — by Provider and Drug.
Transparency — industry payments
Based on CMS Open Payments, 2024; not all care is captured.
$1,438 across 8 records (Open Payments 2024)
Open Payments discloses payments and transfers of value (meals, travel, consulting, research, royalties) from drug and device makers to providers. This is a transparency signal, not a verdict — such payments are legal and common, and their presence is neither an endorsement nor a criticism. Source: CMS Open Payments, program year 2024.
Practice location
Mailing address
Registry dates
- Enumerated
- 2006-08-30
- Last updated
- 2016-10-28
Frequently asked questions
- What is William Gwin's NPI number?
- William Gwin's National Provider Identifier (NPI) is 1598875882, a unique 10-digit ID issued by CMS for use in standard healthcare transactions.
- What is William Gwin's specialty?
- William Gwin is listed in the NPPES registry with a primary specialty of Medical Oncology Physician (Allopathic & Osteopathic Physicians).
- Where is William Gwin located?
- William Gwin's practice location on file with NPPES is 325 9th Ave, Seattle, WA 98104-2499.
- What is William Gwin's phone number?
- The practice phone number listed in the NPPES registry for William Gwin is (206) 744-5100.
- Does William Gwin accept Medicare?
- William Gwin is approved to bill Medicare according to CMS PECOS enrollment data (2026.04.01). Confirm current participation with the provider before scheduling.
- Is William Gwin's NPI active?
- Yes — William Gwin's NPI (1598875882) is active in the NPPES registry as of the last update on 2016-10-28.
Source: CMS NPPES Data Dissemination (June 2026). NPI Central is not affiliated with CMS. Data is provided as-is from the public registry.