Glenn Geoffrey Preston, M.D.
Hematology & Oncology Physician · Spencer, IA
Glenn Geoffrey Preston, M.D. is a hematology & oncology physician with a practice address in Spencer, Iowa, and NPI 1194796243, issued on Jan 27, 2006. Check the license (Iowa 40571, as entered in NPPES) on the Iowa Board of Medicine; the Medicare figures below come from public CMS files.
- Name
- Glenn Geoffrey Preston
- Credential
- M.D.
- Primary taxonomy
- Hematology & Oncology Physician 207RH0003X
- License number
- 40571 IA
Self-reported in NPPES; status is on the state search - Practice location
- 1200 1St Ave E, Spencer, IA 51301
- Phone
- (712) 264-6550
- Enumerated
- Jan 27, 2006
- Record last updated
- Apr 19, 2013 (not updated in 13 years: call before relying on the address or phone)
- Fax
- (712) 264-6553
- Medicaid ID
- 181115001 TX
- Medicare enrollment
- Enrolled (PECOS I20230413001270); accepts Medicare assignment
- Medical or professional school
- University Of Missouri, Columbia School Of Medicine, 1995
- Telehealth
- Offers telehealth (CMS)
- Entity
- Type 1 · individual
8 nearest hematology & oncology physician records → All 90 in Iowa → Look up another NPI →
Also registered at 1200 1St Ave E
A shared address usually means a shared clinic or building; it does not show who employs whom.
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Verify Glenn Geoffrey Preston in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersIowa Board of Medicine
Search for license 40571Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
36% more Medicare Part D claims than the average hematology & oncology physician in 2024
1,192 Medicare Part D claims for 263 beneficiaries, against an average of 877 among the 10,784 providers of this specialty who prescribed in Part D. Brand-name drugs were 15% of claims. 114 claims were for opioids.
Most prescribed
- Anastrozole92 claims
- Prednisone81 claims
- Prochlorperazine Maleate74 claims
- Hydrocodone-Acetaminophen68 claims
- Ondansetron Odt65 claims
- Dexamethasone52 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: $125.00
1 payment: food and beverage; the largest payer was Janssen Biotech, Inc. 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.
2 hospitals and group practices
- Mymichigan Medical Center AlpenaAlpena, MI · Acute Care Hospitals3 of 5 stars
- Mymichigan Medical Center TawasTawas City, MI
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through); hospitals matched to CMS Hospital General Information (Care Compare) (data.cms.gov). Star ratings are CMS hospital ratings, not ratings of this provider.
Glenn Geoffrey Preston among 90 hematology & oncology physician records in Iowa
Glenn Geoffrey Preston, M.D. is one of 90 hematology & oncology physician records with a practice address in Iowa. 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 19% of them.
- NPI issued2006 · 19% of these records are older, 46% newer
- In a Medicare fileYes · 74% of these records are
- In the CMS Doctors and Clinicians fileYes · 61% of these records are
- Graduated1995 · median 2003 among the 55 with a school on file
- Record last updated2013 · 60% 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 Iowa 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 Iowa
There are 90 hematology & oncology physician records in Iowa.
All 90 in Iowa → Every provider in Spencer → Hematology & Oncology Physician nationwide →
The 8 hematology & oncology physician records with the nearest ZIP codes
- Chandana Javvaji, M.D.Sioux City, IA 511011821437716
- Stephen Kahanic, MDSioux City, IA 511011962474155
- John Michalak, M.D.Sioux City, IA 511011497727663
- Radha Rao, M.D.Sioux City, IA 511011699746016
- Donald Wender, M.D.Sioux City, IA 511011861463275
- Sakeer Hussain, M.D.Council Bluffs, IA 515031952423071
- Mukund Nadipuram, MDWaterloo, IA 507021962444349
- Hussain Naseri, M.D.Waterloo, IA 507021154646149
Common questions
What is Glenn Geoffrey Preston, M.D.'s NPI number?
Glenn Geoffrey Preston, M.D.'s National Provider Identifier (NPI) is 1194796243, issued on Jan 27, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Glenn Geoffrey Preston, M.D. located?
The NPPES record lists a practice address at 1200 1St Ave E, Spencer, IA, 51301. Phone: (712) 264-6550. Providers update this record themselves, so call before visiting.
How can I verify Glenn Geoffrey Preston, M.D.'s license?
NPPES lists Iowa license number 40571, as entered by the provider. Search the Iowa Board of Medicine at https://dial.iowa.gov/about-dial/boards-and-commissions/medicine. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Glenn Geoffrey Preston, M.D. prescribe under Medicare Part D?
In 2024, Glenn Geoffrey Preston, M.D. had 1,192 Medicare Part D claims for 263 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.