Shannon E. O'Mahar, MD
Hematology & Oncology Physician · Madison, WI
Shannon E. O'Mahar, MD is a hematology & oncology physician with a practice address in Madison, Wisconsin, and NPI 1366569899, issued on Mar 22, 2007. Check the license (Wisconsin 52434-020, as entered in NPPES) on the Wisconsin Medical Examining Board; the Medicare figures below come from public CMS files.
- Name
- Shannon E. O'Mahar
- Credential
- MD
- Primary taxonomy
- Hematology & Oncology Physician 207RH0003X
- License number
- 52434-020 WI
Self-reported in NPPES; status is on the state search - Practice location
- 1200 John Q Hammons Dr, Madison, WI 53717
- Phone
- (608) 410-2700
- Enumerated
- Mar 22, 2007
- Record last updated
- Oct 27, 2020 (not updated in 6 years: call before relying on the address or phone)
- Fax
- (608) 410-2905
- Medicaid ID
- 1366569899 WI
- Medicare enrollment
- Enrolled (PECOS I20121023000494); accepts Medicare assignment
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest hematology & oncology physician records → All 295 in Wisconsin → Look up another NPI →
Also registered at 1200 John Q Hammons Dr
A shared address usually means a shared clinic or building; it does not show who employs whom.
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- Peter Beatty, MDHematology & Oncology Physician1447206784
- Susan HalwegPharmacist1912195116
- Bradley Lemke, MDOphthalmology Physician1437244621
- Sarah Moore, M.D.Psychiatry Physician1598715666
- Michael Shapiro, M.D.Ophthalmology Physician1669455044
Verify Shannon E. O'Mahar in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersWisconsin Medical Examining Board
Search for license 52434-020Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
3.1 times the Medicare Part D claims of the average hematology & oncology physician in 2024
2,751 Medicare Part D claims for 324 beneficiaries, against an average of 877 among the 10,784 providers of this specialty who prescribed in Part D. Brand-name drugs were 31% of claims. 102 claims were for opioids.
Most prescribed
- Acyclovir293 claims
- Revlimid217 claims
- Dexamethasone157 claims
- Hydroxyurea156 claims
- Anastrozole120 claims
- Prednisone117 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: $19.06
1 payment: food and beverage; the largest payer was Novartis Pharmaceuticals Corporation. The 8,560 providers of this specialty with any payment received $7,481.41 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
- Dean Health Systems IncMadison, WI
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Shannon E. O'Mahar among 295 hematology & oncology physician records in Wisconsin
Shannon E. O'Mahar, MD is one of 295 hematology & oncology physician records with a practice address in Wisconsin. 82% 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 41% of them.
- NPI issued2007 · 41% of these records are older, 46% newer
- In a Medicare fileYes · 82% of these records are
- In the CMS Doctors and Clinicians fileYes · 74% of these records are
- Graduated2005 · median 2004 among the 217 with a school on file
- Record last updated2020 · 51% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207RH0003X and a Wisconsin practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
Hematology & Oncology Physician providers in Wisconsin
There are 295 hematology & oncology physician records in Wisconsin.
All 295 in Wisconsin → Every provider in Madison → Hematology & Oncology Physician nationwide →
The 8 hematology & oncology physician records with the nearest ZIP codes
- Peter Beatty, MDMadison, WI 537171447206784
- Charles Diggs, MDMadison, WI 537171710933965
- Linh Khuu, MDMadison, WI 537171801884218
- Trevor Dennie, MDMadison, WI 537151710030333
- Thomas Hanzlik, M.DMadison, WI 537151235586702
- Elyse Harris, MDMadison, WI 537151215324090
- Roy Kim, M.D.Madison, WI 537151942316286
- Lisa Lepeak, M.D.Madison, WI 537151053357384
Common questions
What is Shannon E. O'Mahar, MD's NPI number?
Shannon E. O'Mahar, MD's National Provider Identifier (NPI) is 1366569899, issued on Mar 22, 2007. An NPI identifies a provider in billing; it is not a license.
Where is Shannon E. O'Mahar, MD located?
The NPPES record lists a practice address at 1200 John Q Hammons Dr, Madison, WI, 53717. Phone: (608) 410-2700. Providers update this record themselves, so call before visiting.
How can I verify Shannon E. O'Mahar, MD's license?
NPPES lists Wisconsin license number 52434-020, as entered by the provider. Search the Wisconsin Medical Examining Board at https://dsps.wi.gov/Pages/BoardsCouncils/MEB/Default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Shannon E. O'Mahar, MD prescribe under Medicare Part D?
In 2024, Shannon E. O'Mahar, MD had 2,751 Medicare Part D claims for 324 beneficiaries; the average among hematology & oncology physician prescribers was 877. 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.