NPPES file of Aug 9, 2026

Medical Oncology Physician in California

447 NPPES records list medical oncology physician with a practice address in California, 1.1 per 100,000 residents, the 31st highest rate of 51. Stanford and San Francisco have the most; each record links to the provider's NPI and the California license search. Page 9 of 9.

CMS NPPES registry, file of Aug 9, 2026; 2023 Census estimates · NUCC 207RX0202X · method

Written with AI tools from the named public files; every figure is computed from those files (how it is made).

Stanford has the most, 82

  1. Stanford82
  2. San Francisco53
  3. Duarte48
  4. Los Angeles39
  5. San Diego19

Medical Oncology Physician records in California

  1. Przemyslaw Twardowski, MDSanta Monica, CA 904041942317987
  2. Ari Umutyan, M.D.Saint Helena, CA 945741275516171
  3. Gargi Upadhyaya, M.D.Pasadena, CA 911061013957190
  4. Jennifer Valerin, M.D.Orange, CA 928681376770255
  5. Katherine Vanloon, MD MPHSan Francisco, CA 941151497910335
  6. Katarina Vasiljevic, M.D.Irvine, CA 926181770042731
  7. Marina Vaysburd, M.D.Beverly Hills, CA 902111689784712
  8. Ana Velazquez, MD MSCSan Francisco, CA 941101144647421
  9. Alan Venook, MDSan Francisco, CA 941431487618831
  10. Ajay Verma, M.D.Redding, CA 960011386755403
  11. Victoria Villaflor, M.D.Orange, CA 928681154380582
  12. Manasa Vulchi, M.D.Rancho Mirage, CA 922701760739296
  13. Klaus Wagner, MD PHDSan Diego, CA 921611841458023
  14. James Waisman, M.DDuarte, CA 910101356391270
  15. Barliz Waissengrin, MDLos Angeles, CA 900481578407904
  16. Heather Wakelee, MDStanford, CA 943051720137094
  17. Evan WalkerSan Francisco, CA 941431982098380
  18. Siao-Yi Wang, M.D.Sacramento, CA 958171134540859
  19. Wei Wang, MD, PHDSan Francisco, CA 941151861482853
  20. Wenge Wang, M.D., PH.D.Duarte, CA 910101497047195
  21. Howard West, MDDuarte, CA 910101346324068
  22. Jeffrey WiezorekThousand Oaks, CA 913201467600288
  23. Christopher Williams, M.D.Eureka, CA 955011588899363
  24. Byron Wilson, M.D.Castro Valley, CA 945461992736367
  25. Charles Wiseman, M.D.Beverly Hills, CA 902111962493551
  26. Slawomir Wojtowicz-Praga, M.D.South San Francisco, CA 940801720262330
  27. Nora Wu, M.D.Sacramento, CA 958161487754461
  28. Marin Xavier, MDSan Diego, CA 921031437211372
  29. Bing Xia, M.D.Los Angeles, CA 900891154611218
  30. Yan Xing, MDDuarte, CA 910101184987166
  31. Melisa Yajima, MDSan Francisco, CA 941431215236682
  32. Kenneth Yamamoto, MDDaly City, CA 940151467545368
  33. Shihfan Yeh, M.D.Vallejo, CA 945891013145556
  34. Yun Yen, MDDuarte, CA 910101003827486
  35. Kevin Yoon, M.D.Lancaster, CA 935341972092674
  36. Patricia Young, MDLos Angeles, CA 900481285957589
  37. Arlene Yu, MD, MBACerritos, CA 907031144744772
  38. Yuan Yuan, M.D., PH.D.Pasadena, CA 911051073664660
  39. Karen Yun, M.D.San Diego, CA 921031720519234
  40. Peter ZangDuarte, CA 910101962039669
  41. Cong Zhang, M.D., PH.D.Woodland, CA 956951356553317
  42. Fan Zhang, MDSanta Rosa, CA 954031619051695
  43. Xiaojie ZhangSan Diego, CA 921031700374188
  44. Maggie Zhou, MDStanford, CA 943051740741982
  45. Ming Zhou, MDModesto, CA 953551619933850
  46. Xiaolin Zhu, M.D., PH.D.San Francisco, CA 941431861933129
  47. Behrooz Zidehsarai, MDRedding, CA 960011639177975

Source: CMS NPPES, primary taxonomy 207RX0202X: records by practice city and the list of records, file of Aug 9, 2026.

California ranks 31 of 51 per resident

  1. Virginia1.2
  2. Kansas1.2
  3. Wisconsin1.2
  4. California1.1
  5. Indiana1.1
  6. Idaho1.1
  7. 50 states and D.C.1.7

Source: CMS NPPES, primary taxonomy 207RX0202X by practice state, file of Aug 9, 2026; records per 100,000 residents, 2023 Census estimates.

82.1% of these records appear in a Medicare file, against 81.8% nationally

A Medicare file here is Part D prescribing (2024), a MIPS score (2023), an Open Payments record (2024) or Medicare group billing (CMS Doctors and Clinicians). A record outside them may still see patients: these files cover Medicare only.

  1. California82.1%
  2. United States81.8%

Medical Oncology Physician records in California, measured

  • In a Medicare file367 of 447 · 82.1% here, 81.8% nationally
  • In the CMS Doctors and Clinicians file313 · 70.0% here, 72.5% nationally
  • Not updated in five years or more184 · 41.2% here, 49.3% nationally
  • Median graduation year2004 · the 312 records with a school on file

Source: CMS NPPES, file of Aug 9, 2026 (primary taxonomy 207RX0202X); CMS Medicare Part D Prescribers 2024, MIPS 2023, Open Payments 2024 and Doctors and Clinicians, matched by NPI.

What the count covers

447 NPPES records list medical oncology physician (207RX0202X) as their primary taxonomy with a practice address in California: 1.1 per 100,000 residents against 1.7 nationally (50 states and D.C.). Stanford has 82 of them (18%).

A record is a registration a provider made and keeps up to date: it shows neither that the provider is licensed nor that they still practice there. The state's own license search is the check.

States with a similar number

  1. Massachusetts421
  2. Texas547
  3. New York548
  4. Florida561

States with a similar rate per 100,000

  1. Indiana1.1
  2. Wisconsin1.2
  3. Idaho1.1
  4. Kansas1.2

The largest states

  1. Florida561
  2. New York548
  3. Texas547
  4. Massachusetts421
  5. Pennsylvania265

Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy; 2023 Census population estimates. A registry record is not a license.

Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.