✅ Official notice on file. Marin Cancer Care filed this data breach notice with the California Attorney General on Apr 23, 2026. Compare it with the letter you received: the official copy is linked below.
Marin Cancer Care reported a data breach caused by unauthorized access to its computer network.
Key facts
| Unauthorized access | Nov 22, 2025 – Dec 6, 2025 |
|---|---|
| Discovered | Dec 8, 2025 |
| Incident type | Network intrusion |
| Letter sent | Apr 23, 2026 |
| Reported to California AG | Apr 23, 2026 |
| Company helpline | 1-833-877-3965 |
Free credit monitoring
Marin Cancer Care is offering 12 months of Cyberscout (TransUnion) at no cost to people who received the letter. Enroll at bfs.cyberscout.com/activate using the activation code printed on your letter.
What to do now
- Get your free credit reports at AnnualCreditReport.com and look for accounts you do not recognize.
- Call the Marin Cancer Care helpline at 1-833-877-3965 if you have questions about your letter.
Timeline
- Nov 22, 2025 — Unauthorized access begins
- Dec 8, 2025 — Marin Cancer Care discovers the incident
- Apr 23, 2026 — Notification letters sent
- Apr 23, 2026 — Breach reported to the California Attorney General
Other recent data breaches
- Deposition Solutions, LLC data breach
- Mercadien, P.C. CPAs data breach
- Toyo Tire Holdings of Americas Inc. data breach
- STS Aviation Group data breach
- Alma Family Services data breach
Source: notification letter and filing submitted by Marin Cancer Care to the California Attorney General. BreachLetter is not affiliated with Marin Cancer Care. Details extracted from the official letter; always follow the instructions in your own copy.