John S. Sierocki, M.D.
Medical Oncology Physician · Princeton, NJ
John S. Sierocki, M.D. is a medical oncology physician with a practice address in Princeton, New Jersey, and NPI 1487792354, issued on Feb 2, 2007. Check the license (New Jersey 25MA03428100, as entered in NPPES) on the New Jersey State Board of Medical Examiners; the Medicare figures below come from public CMS files.
- Name
- John S. Sierocki
- Credential
- M.D.
- Primary taxonomy
- Medical Oncology Physician 207RX0202X
- License number
- 25MA03428100 NJ
Self-reported in NPPES; status is on the state search - Practice location
- 419 N Harrison St, Princeton, NJ 08540
- Phone
- (609) 924-9300
- Enumerated
- Feb 2, 2007
- Record last updated
- May 16, 2008 (not updated in 18 years: call before relying on the address or phone)
- Fax
- (609) 430-9481
- Medicaid ID
- 2441004 NJ
- Medicare enrollment
- Enrolled (PECOS I20100318000541); accepts Medicare assignment
- Medical or professional school
- Hahnemann University College Of Medicine, 1973
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest medical oncology physician records → All 140 in New Jersey → Look up another NPI →
Also registered at 419 N Harrison St
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify John S. Sierocki in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersNew Jersey State Board of Medical Examiners
Search for license 25MA03428100Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
3.9 times the Medicare Part D claims of the average medical oncology physician in 2024
2,749 Medicare Part D claims for 258 beneficiaries, against an average of 703 among the 4,230 providers of this specialty who prescribed in Part D. 57 claims were for opioids.
Most prescribed
- Levothyroxine Sodium183 claims
- Pantoprazole Sodium133 claims
- Letrozole88 claims
- Omeprazole87 claims
- Amlodipine Besylate81 claims
- Losartan Potassium72 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: $89.95
1 payment: education; the largest payer was Gilead Sciences, Inc. The 3,343 providers of this specialty with any payment received $11,773.47 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
- Princeton Medical Group,p.a.Princeton, NJ
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
John S. Sierocki among 140 medical oncology physician records in New Jersey
John S. Sierocki, M.D. is one of 140 medical oncology physician records with a practice address in New Jersey. 78% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2007, is newer than 52% of them.
- NPI issued2007 · 52% of these records are older, 41% newer
- In a Medicare fileYes · 78% of these records are
- In the CMS Doctors and Clinicians fileYes · 69% of these records are
- Graduated1973 · median 2001 among the 96 with a school on file
- Record last updated2008 · 40% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RX0202X and a New Jersey practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Medical Oncology Physician providers in New Jersey
There are 140 medical oncology physician records in New Jersey.
All 140 in New Jersey → Every provider in Princeton → Medical Oncology Physician nationwide →
The 8 medical oncology physician records with the nearest ZIP codes
- Jeffrey Humphrey, M.D.Princeton, NJ 085401801124094
- Rachel Humphrey, M.D.Princeton, NJ 085401679898779
- Peter Graham, MDPennington, NJ 085341841385226
- Dongyoun Lee, M.D.Pennington, NJ 085341073919312
- Laurie Smaldone AlsupPennington, NJ 085341639446628
- Pauline Lerma, MDHamilton, NJ 086901447334172
- Ethan Wasserman, MDHamilton, NJ 086901811104292
- Peter Abdelmessieh, DORobbinsville, NJ 086911073803896
Common questions
What is John S. Sierocki, M.D.'s NPI number?
John S. Sierocki, M.D.'s National Provider Identifier (NPI) is 1487792354, issued on Feb 2, 2007. An NPI identifies a provider in billing; it is not a license.
Where is John S. Sierocki, M.D. located?
The NPPES record lists a practice address at 419 N Harrison St, Princeton, NJ, 08540. Phone: (609) 924-9300. Providers update this record themselves, so call before visiting.
How can I verify John S. Sierocki, M.D.'s license?
NPPES lists New Jersey license number 25MA03428100, as entered by the provider. Search the New Jersey State Board of Medical Examiners at https://newjersey.mylicense.com/verification/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does John S. Sierocki, M.D. prescribe under Medicare Part D?
In 2024, John S. Sierocki, M.D. had 2,749 Medicare Part D claims for 258 beneficiaries; the average among medical oncology physician prescribers was 703. 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.