Marin Cancer Care

Disclosed Feb 6, 202627,332 affectedConfirmed

The covered entity (CE), Marin Cancer Care, reported that it experienced a cybersecurity incident that affected the protected health information (PHI) of 27,332 individuals. The PHI involved included demographic, clinical, and financial information. The CE notified HHS, affected individuals, and provided media notice. In response to the breach, the CE implemented additional administrative and technical safeguards.

What is known

People affected	27,332 (as reported to HHS)
Disclosed	Feb 6, 2026
Happened	Nov 22, 2025
Attack	Hacking
Data exposed	NamesHealth
Sector	Healthcare · US
Status	Confirmed

Sources

Official noticeoag.ca.gov

California Attorney General breach notice: Marin Cancer Care

Official noticeago.vermont.gov

Vermont Attorney General breach report: Marin Cancer Care

Official noticeocrportal.hhs.gov

HHS OCR breach report (archive, resolved): Marin Cancer Care (Healthcare Provider, CA)

Notices filed

TotalFeb 6

HHS archive27,332 people

Residents of CAApr 23

California AGCount not stated

Residents of VTApr 23

Vermont AG2 people

History of this record

attack2026-09-25

unknown to hackingby backfillSource

records_basis2026-09-25

empty to hhsby backfillSource

records2026-09-25

empty to 27332by backfillSource

disclosed2026-09-25

2026-04-23 to 2026-02-06by backfillSource

summary2026-09-25

empty to The covered entity (CE), Marin Cancer Care, reported that it experienced a cybersecurity incident that affected the protected health information (PHI) of 27,332 individuals. The PHI involved included demographic, clinical, and financial infby backfillSource

data_types2026-09-25

[] to ["names","health"]by backfillSource

Added2026-09-25

First recordedby backfillSource

First seen 2026-09-25 (California AG), confirmed by California AG. Record counts are as reported. Not legal advice.

Everything about Marin Cancer Care