BreachCensus

21st Century Oncology

United States of America

21st Century Oncology is an organisation in Washington. It appears on the California Attorney General breach-notification register, the Washington State Attorney General breach-notification register and the Wisconsin DATCP data breach list with 1 confirmed incident; the most recent notice was filed on March 4, 2016.

Data as of September 6, 2026.

Confirmed incident

Filed in WA, CA and WI — Unauthorized Access/Disclosure

The same incident was filed separately with 3 jurisdictions within a few days of each other (WA, CA and WI) — shown here as one incident.

Occurred
October 3, 2015
Disclosed
March 4, 2016

Timeline

  1. March 4, 2016
    Reported to regulator Regulator

    WA AG breach notification: 2,802 Washington residents affected

    source
  2. March 4, 2016
    Reported to regulator Regulator

    CA AG breach notification: an unknown number of California residents affected

    source
  3. March 4, 2016
    Reported to regulator Regulator

    WI AG breach notification: an unknown number of Wisconsin residents affected

    source

Litigation

  • Possible litigation — multiple candidate dockets found, not yet resolved to a single case.
What a Washington notice means

Governed by RCW 19.255.010. Notice to the Attorney General is required when a breach affects more than 500 Washington residents.

Note: the count is Washington residents only, not a total.

Washington breach-notification register ↗

What a California notice means

Governed by Cal. Civ. Code §1798.82. A copy of the notification must be sent to the Attorney General when a single breach requires notifying more than 500 California residents.

Note: no affected-count is published on this register.

California breach-notification register ↗

What a Wisconsin notice means

Governed by Wis. Stat. §134.98. No state agency must be notified. Affected individuals must be told within 45 days, and the national credit bureaus too when 1,000 or more people are notified; DATCP lists breaches reported to it or found to affect Wisconsin consumers.

Note: the count is Wisconsin residents only when published, not a total; many notices do not include one.

Wisconsin breach-notification register ↗