Jaroslaw Jac, MD
Hematology & Oncology Physician · Westborough, MA
Jaroslaw Jac, MD is a hematology & oncology physician with a practice address in Westborough, Massachusetts, and NPI 1326029802, issued on Nov 10, 2005. Check the license (Massachusetts 238060, as entered in NPPES) on the Massachusetts Board of Registration in Medicine; the Medicare figures below come from public CMS files.
- Name
- Jaroslaw Jac
- Credential
- MD
- Primary taxonomy
- Hematology & Oncology Physician 207RH0003X
- License numbers
- 238060 MA
MD13980 ME
35312 NH
J9106 TX
Self-reported in NPPES; status is on the state search - Practice location
- 150 Flanders RD, Westborough, MA 01581
- Phone
- (508) 870-2222
- Enumerated
- Nov 10, 2005
- Record last updated
- Jul 24, 2026
- Medicaid IDs
- 139379518 TX
110081560/A MA - Medicare enrollment
- Enrolled (PECOS I20090121000341); accepts Medicare assignment
- Entity
- Type 1 · individual
8 nearest hematology & oncology physician records → All 461 in Massachusetts → Look up another NPI →
Also registered at 150 Flanders RD
A shared address usually means a shared clinic or building; it does not show who employs whom.
- Toshal Hallowell, RPHPharmacist1619861937
- William Hartzell, M.D.Pulmonary Disease Physician1417938986
- Michael Hoang, PHARMDPharmacist1770108250
- Samina Khan, MA, CCC-AAudiologist1619116308
- Gregory Malloy, M.D.Physical Medicine & Rehabilitation Physician1427164342
- Jennifer Martin, MPTPhysical Therapist1487948766
Verify Jaroslaw Jac in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMassachusetts Board of Registration in Medicine
Search for license 238060Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
43% fewer Medicare Part D claims than the average hematology & oncology physician in 2024
504 Medicare Part D claims for 98 beneficiaries, against an average of 877 among the 10,784 providers of this specialty who prescribed in Part D. Brand-name drugs were 24% of claims. 35 claims were for opioids.
Most prescribed
- Prochlorperazine Maleate44 claims
- Sulfamethoxazole-Trimethoprim32 claims
- Xtandi27 claims
- Acyclovir21 claims
- Dexamethasone21 claims
- Oxycodone Hcl21 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: $180.52
8 payments; by number, the most common kind was food and beverage; the largest payer was E.R. Squibb & Sons, L.L.C. 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 2 group practices
- Associated Physicians OF Harvard Medical Faculty Physicians AT Beth ISMilton, MA
- Community Medical Associates, Inc.Methuen, MA
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Jaroslaw Jac among 461 hematology & oncology physician records in Massachusetts
Jaroslaw Jac, MD is one of 461 hematology & oncology physician records with a practice address in Massachusetts. 75% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2005, is newer than 0% of them.
- NPI issued2005 · 0% of these records are older, 86% newer
- In a Medicare fileYes · 75% of these records are
- In the CMS Doctors and Clinicians fileYes · 66% of these records are
- Graduated1990 · median 2004 among the 303 with a school on file
- Record last updated2026 · 62% 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 Massachusetts 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 Massachusetts
There are 461 hematology & oncology physician records in Massachusetts.
All 461 in Massachusetts → Every provider in Westborough → Hematology & Oncology Physician nationwide →
The 8 hematology & oncology physician records with the nearest ZIP codes
- Richard Horner, M.D.Worcester, MA 016051104800465
- Vijay Kasturi, M.D.Worcester, MA 016051821071077
- Nahida Islam, M.D.Worcester, MA 016061568669646
- Edison Tsui, MDWorcester, MA 016061568876340
- Mohammed Wazir, M.D.Worcester, MA 016061144672064
- Kevin Brown, MDWorcester, MA 016081760401384
- Saleem Khanani, MDWorcester, MA 016081255306643
- James Rooney, M.D.Worcester, MA 016081215983358
Common questions
What is Jaroslaw Jac, MD's NPI number?
Jaroslaw Jac, MD's National Provider Identifier (NPI) is 1326029802, issued on Nov 10, 2005. An NPI identifies a provider in billing; it is not a license.
Where is Jaroslaw Jac, MD located?
The NPPES record lists a practice address at 150 Flanders RD, Westborough, MA, 01581. Phone: (508) 870-2222. Providers update this record themselves, so call before visiting.
How can I verify Jaroslaw Jac, MD's license?
NPPES lists Massachusetts license number 238060, as entered by the provider. Search the Massachusetts Board of Registration in Medicine at https://findmydoctor.mass.gov/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Jaroslaw Jac, MD prescribe under Medicare Part D?
In 2024, Jaroslaw Jac, MD had 504 Medicare Part D claims for 98 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.