We don’t sell ranking and don’t accept payment to move a provider up the list. For final hire decisions, verify licensing, insurance, and references directly with the applicable licensing or credentialing body.
No bulk-licensing source family is currently ingested for this vertical. Hire-time checking still routes through the body named above.
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California has 619 active oncologists (1.57 per 100,000 residents) — ranked 31 of 51 U.S. states + DC. Source: CMS NPPES NPI Registry + U.S. Census Bureau, snapshot 2026-05-06. Threshold for "underserved" in the parent study: 3 per 100,000. Citation: Fonteum Research, /research/oncology-supply-by-state-2026.
Source provenance
U.S. Centers for Medicare & Medicaid Services NPI Registry (NPPES) — public API
U.S. Census Bureau Population Estimates Program, 2024 Vintage (V2024)
This figure measures density (per-capita supply), not access. Drive time, appointment availability, insurance acceptance, and wait times are not modeled here.
The CMS NPPES registry counts NPI-1 individual providers with the relevant taxonomy code. It does not capture PA-led or NP-led practices that operate under a different taxonomy.
NPPES does not publish a county-level field of practice in its public API. County- and ZIP-scoped queries surface state-level density, with the geographic context preserved on this page.
Population is the U.S. Census Bureau 2024 vintage estimate. Population shifts post-2024 are not yet reflected.
The "underserved" threshold is the parent study's transparent baseline cutoff; it is not a regulatory or clinical definition. See the parent study for the rationale.