William W. Chou, MD
Radiation Oncology Physician · Mission Viejo, CA
William W. Chou, MD is a radiation oncology physician with a practice address in Mission Viejo, California, and NPI 1790713253, issued on Jun 30, 2006. Check the license (California A94743, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- William W. Chou
- Credential
- MD
- Primary taxonomy
- Radiation Oncology Physician 2085R0001X
- License number
- A94743 CA
Self-reported in NPPES; status is on the state search - Practice location
- 27799 Medical Center RD Ste 120, Mission Viejo, CA 92691
- Phone
- (949) 573-9560
- Enumerated
- Jun 30, 2006
- Record last updated
- Nov 9, 2020 (not updated in 6 years: call before relying on the address or phone)
- Fax
- (949) 364-4276
- Medicaid IDs
- GR0103710 CA
00A947430 CA - Medicare enrollment
- Enrolled (PECOS I20060807000283); accepts Medicare assignment
- Medical or professional school
- Stanford University School Of Medicine, 2001
- Entity
- Type 1 · individual
8 nearest radiation oncology physician records → All 735 in California → Look up another NPI →
Also registered at 27799 Medical Center RD Ste 120
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Carolyn Young, MDRadiation Oncology Physician1598795999
Verify William W. Chou in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license A94743Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
2.8 times the Medicare Part D claims of the average radiation oncology physician in 2024
374 Medicare Part D claims for 115 beneficiaries, against an average of 134 among the 4,851 providers of this specialty who prescribed in Part D. Brand-name drugs were 20% of claims. 38 claims were for opioids.
Most prescribed
- Tamsulosin Hcl111 claims
- Orgovyx21 claims
- Ssd21 claims
- Alfuzosin Hcl Er19 claims
- Hydrocodone-Acetaminophen19 claims
- Silver Sulfadiazine13 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Industry payments in 2024: $19.17
1 payment: food and beverage; the largest payer was Sumitomo Pharma America, Inc. The 3,275 providers of this specialty with any payment received $1,897.85 on average. Payments are reported by manufacturers, not by the provider, and are not a sign of wrongdoing.
Source: CMS Open Payments, program year 2024 (openpaymentsdata.cms.gov); average among providers of this specialty with at least one payment.
Bills Medicare through one group practice
- Mission Viejo Radiation Oncology CorpMission Viejo, CA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
William W. Chou among 735 radiation oncology physician records in California
William W. Chou, MD is one of 735 radiation oncology physician records with a practice address in California. 83% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 16% of them.
- NPI issued2006 · 16% of these records are older, 55% newer
- In a Medicare fileYes · 83% of these records are
- In the CMS Doctors and Clinicians fileYes · 74% of these records are
- Graduated2001 · median 2005 among the 545 with a school on file
- Record last updated2020 · 55% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 2085R0001X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Radiation Oncology Physician providers in California
There are 735 radiation oncology physician records in California.
All 735 in California → Every provider in Mission Viejo → Radiation Oncology Physician nationwide →
The 8 radiation oncology physician records with the nearest ZIP codes
- Elizabeth Hyden, MDMission Viejo, CA 926911780610196
- Michael Lock, MDMission Viejo, CA 926911154357564
- Carolyn Young, MDMission Viejo, CA 926911598795999
- Chu-Pei Feng, M.D.Santa Ana, CA 927051922010073
- Sharon Lee, M.D.Santa Ana, CA 927051215105432
- Ernest Ngo, M.D.Santa Ana, CA 927051366454415
- Regiane De Andrade, M.D.Fountain Valley, CA 927081922352467
- Asif Harsolia, M.D.Fountain Valley, CA 927081376565374
Common questions
What is William W. Chou, MD's NPI number?
William W. Chou, MD's National Provider Identifier (NPI) is 1790713253, issued on Jun 30, 2006. An NPI identifies a provider in billing; it is not a license.
Where is William W. Chou, MD located?
The NPPES record lists a practice address at 27799 Medical Center RD Ste 120, Mission Viejo, CA, 92691. Phone: (949) 573-9560. Providers update this record themselves, so call before visiting.
How can I verify William W. Chou, MD's license?
NPPES lists California license number A94743, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does William W. Chou, MD prescribe under Medicare Part D?
In 2024, William W. Chou, MD had 374 Medicare Part D claims for 115 beneficiaries; the average among radiation oncology physician prescribers was 134. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it 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.