Provider records sourced from NPPES (CMS National Plan & Provider Enumeration System). Data current as of October 4, 2026.
NPIDirectory

William Breen, MD

Individual provider Radiation Oncology Physician · NPI 1437683562

William Breen, MD practises Radiation Oncology in Rochester, Minnesota. Qualified in 2017, 9 years ago. Practices with Mayo Clinic, a 4,796-clinician group and accepts Medicare assignment. Licensed in Minnesota and Wisconsin.

Years since qualifying
9
Licensed in
MN, WI
In the registry since
2017
Specialties on file
2
What do these letters mean?
MD — Doctor of Medicine
A physician who completed allopathic medical school.

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Practice location Address checks out

200 1st St SW
Rochester, MN 55905
Phone: (507) 284-2511
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Pin is approximate — placed at the ZIP-code centre, not the exact door.

Specialties & licences

Radiation Oncology Physician (primary) Taxonomy 2085R0001X · Licence 64064 (MN)
Radiation Oncology Physician Taxonomy 2085R0001X · Licence 81689 (WI)

Record details

NPI number1437683562
Entity typeIndividual (Type 1)
GenderMale
Credentials MD
Sole proprietorNo
NPI enumeratedApril 15, 2017
Last updated in NPPESDecember 10, 2025
Certification dateDecember 10, 2025

Medicare enrollment

From the CMS Doctors & Clinicians file — this clinician is enrolled in Medicare.

Medicare specialtyRADIATION ONCOLOGY
Medical schoolOTHER
Graduated 2017 (9 years in practice)
Group practice Mayo Clinic — 4796 clinicians
Accepts Medicare assignment Yes — accepts the Medicare-approved amount
Practice locations4 on file with Medicare

Medicare patients and services, 2024

From the CMS Medicare Physician & Other Practitioners file for calendar year 2024. It counts Original Medicare patients only, so a practice that mostly sees Medicare Advantage or privately insured patients looks smaller here than it is.

Medicare patients234
Services billed 1,955 a service is one billed item, such as a visit, a test or a procedure
Average patient age73

Dollar amounts are not shown. What Medicare pays a practice is gross billings, before staff, premises and tax and including the cost of any drugs it administers, so it is not what a clinician earns.

Practises at

Facilities the CMS Facility Affiliation file lists for this clinician.

Colleagues at Mayo Clinic

Clinicians the CMS Doctors & Clinicians file lists under the same group practice. CMS counts 4796 clinicians in the practice; 12 are shown here.

Other providers in Rochester