Ruth Callaway Warren, DO
Medical Oncology Physician · Green Bay, WI
Ruth Callaway Warren, DO is a medical oncology physician with a practice address in Green Bay, Wisconsin, and NPI 1124096185, issued on Mar 8, 2006. Check the license (Wisconsin 50362, as entered in NPPES) on the Wisconsin Medical Examining Board; the Medicare figures below come from public CMS files.
- Name
- Ruth Callaway Warren
- Credential
- DO
- Primary taxonomy
- Medical Oncology Physician 207RX0202X
- License numbers
- 50362 WI
5101018539 MI
Self-reported in NPPES; status is on the state search - Practice location
- 1726 Shawano Ave, Green Bay, WI 54303
- Phone
- (920) 884-3135
- Enumerated
- Mar 8, 2006
- Record last updated
- Dec 20, 2021 (not updated in 5 years: call before relying on the address or phone)
- Fax
- (920) 884-3144
- Medicaid IDs
- 1124096185 MI
100004011 WI - Medicare enrollment
- Enrolled (PECOS I20091124000158); accepts Medicare assignment
- Medical or professional school
- Midwestern University, Chicago College Of Osteopathic Med, 1999
- Entity
- Type 1 · individual
8 nearest medical oncology physician records → All 69 in Wisconsin → Look up another NPI →
Also registered at 1726 Shawano Ave
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Kamal Kant Singh Abbi, M.D.Medical Oncology Physician1588827778
- Joao Vitor Andreoli Saltao, MDInternal Medicine Physician1851870976
- Mohamed Azab, M.DGastroenterology Physician1013390434
- Melissa Bader, NPFamily Nurse Practitioner1508692724
- Yaw Berko, MDInternal Medicine Physician1003952995
- Jules Blank, M.D.Hematology & Oncology Physician1730273889
Verify Ruth Callaway Warren in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersWisconsin Medical Examining Board
Search for license 50362Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
14% fewer Medicare Part D claims than the average medical oncology physician in 2024
608 Medicare Part D claims for 229 beneficiaries, against an average of 703 among the 4,230 providers of this specialty who prescribed in Part D. Brand-name drugs were 26% of claims. 61 claims were for opioids.
Most prescribed
- Eliquis39 claims
- Tamoxifen Citrate38 claims
- Prednisone31 claims
- Ondansetron Hcl30 claims
- Anastrozole27 claims
- Acyclovir24 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.
Bills Medicare through one group practice
- Ascension NE Wisconsin, IncAppleton, WI
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Ruth Callaway Warren among 69 medical oncology physician records in Wisconsin
Ruth Callaway Warren, DO is one of 69 medical oncology physician records with a practice address in Wisconsin. 74% 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 10% of them.
- NPI issued2006 · 10% of these records are older, 36% newer
- In a Medicare fileYes · 74% of these records are
- In the CMS Doctors and Clinicians fileYes · 67% of these records are
- Graduated1999 · median 2001 among the 46 with a school on file
- Record last updated2021 · 59% 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 Wisconsin 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 Wisconsin
There are 69 medical oncology physician records in Wisconsin.
All 69 in Wisconsin → Every provider in Green Bay → Medical Oncology Physician nationwide →
The 8 medical oncology physician records with the nearest ZIP codes
- Kamal Kant Singh Abbi, M.D.Green Bay, WI 543031588827778
- David Groteluschen, M.D.Green Bay, WI 543031679538011
- Thomas Saphner, M.D.Green Bay, WI 543031700970894
- Alexander Starr, MDGreen Bay, WI 543031790722619
- Evan WenigGreen Bay, WI 543031215460068
- Gerald Bayer, M.D.Green Bay, WI 543011285726729
- James McGovern, M.D.Green Bay, WI 543111053447672
- Maria De Villa, M.D.Green Bay, WI 543131538321252
Common questions
What is Ruth Callaway Warren, DO's NPI number?
Ruth Callaway Warren, DO's National Provider Identifier (NPI) is 1124096185, issued on Mar 8, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Ruth Callaway Warren, DO located?
The NPPES record lists a practice address at 1726 Shawano Ave, Green Bay, WI, 54303. Phone: (920) 884-3135. Providers update this record themselves, so call before visiting.
How can I verify Ruth Callaway Warren, DO's license?
NPPES lists Wisconsin license number 50362, 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 Ruth Callaway Warren, DO prescribe under Medicare Part D?
In 2024, Ruth Callaway Warren, DO had 608 Medicare Part D claims for 229 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.