Breach filing
ArchivedMemorial Sloan Kettering Cancer Center: 18,913 individuals, Mar 2021.
Memorial Sloan Kettering Cancer Center reported a breach of unsecured protected health information to the HHS Office for Civil Rights on 31 March 2021. The filing records the organisation as a healthcare provider in New York and lists 18,913 individuals affected, which makes it the 141st largest of the 511 New York filings on the register and the 223rd largest of the 715 filings submitted nationally in 2021. Among the 45 New York filings made in 2021 it ranks 15th.
Individuals affected
18,913
As reported to HHS
Modelled cost (IBM 2025)
$3.03M
Method shown, not disclosed
Rank in NY
141st
of 511 New York filings
Rank in 2021
223rd
of 715 filings nationally
Section F.1 / The filing
As posted by HHS OCR
Every value below is the portal's own field for this filing, plus its rank within the register.
- Covered entity type
- Healthcare Provider
- Individuals affected
- 18,913
- Breach submission date
- 31 March 2021
- Submission year
- 2021
- Type of breach
- Unauthorized Access/Disclosure
- Location of breached information
- Network Server
- Business associate present
- Yes
- State
- New York (NY)
- Portal status
- listed in the HHS OCR breach portal archive
- Rank in New York by size
- 141st of 511
- Rank in 2021 nationally
- 223rd of 715
- New York median filing
- 5,338 individuals
- Register id (derived)
- NY-20210331-memorial-sloan-kettering-cancer-center
Section F.2 / In context
Where this filing sits in New York and in 2021
OCR classifies the incident as unauthorized access or disclosure, with the breached information held in a network server. Unauthorized Access/Disclosure is the type recorded on 100 of the 511 New York filings (20%) and on 18% of all filings submitted in 2021. Network Server appears on 49% of New York filings.
A business associate is recorded as present on the filing, as it is on 30% of New York filings. At 18,913 individuals the breach is 3.5 times the New York median filing of 5,338 and 4.7 times the national median of 4,000 across all 7,884 filings. It sits in the 10,000 to 99,999 band, which holds 1,938 filings.
As of 28 August 2026 the case is listed in the HHS OCR breach portal archive. OCR's closing summary of the case is reproduced in full below.
New York's breach notification statute (N.Y. Gen. Bus. Law 899-aa) requires notice to affected residents in the most expedient time possible and without unreasonable delay, no later than 30 days after discovery. Its attorney general threshold: all breaches (AG, Dept. of State, State Police). The HIPAA Breach Notification Rule ran alongside it: notice to affected individuals and to HHS without unreasonable delay and no later than 60 days after discovery, which is the clock that put this filing on the portal.
Multiplying 18,913 individuals by IBM's $160 customer-PII cost per record (Cost of a Data Breach 2025, the figure the site's calculator uses) gives a modelled $3.03M; the 2026 edition's $192 gives $3.63M. Both are modelled estimates with the method shown, not costs disclosed by Memorial Sloan Kettering Cancer Center. For scale, IBM's 2026 average cost of a healthcare breach is $6.64M, so this filing models at 0.5 times the sector average.
Section F.3 / OCR closing summary
The portal's archived description, in full
Written by the Office for Civil Rights when the case was closed and reproduced verbatim from the HHS export.
The covered entity (CE), Memorial Sloan Kettering Cancer Center, reported that employees of its business associate misconfigured a server and exposed the protected health information (PHI) of 18,913 individuals. The PHI involved included names, Social Security numbers, dates of birth, addresses, financial information, diagnoses, lab results, medications prescribed, and other treatment information. The CE notified HHS, affected individuals, the media, and provided substitute notice. In response to the breach, the CE provided free credit monitoring and fraud protection services, sanctioned workforce members responsible for the breach, and took the affected network server offline.
Section F.5 / Modelled cost
18,913 individuals through IBM's per-record figures
Modelled cost / method shown, not a disclosed cost
ModelledIBM 2025 customer PII, $160 per record
$3.03M
18,913 x $160
IBM 2026 customer PII, $192 per record
$3.63M
18,913 x $192
Method: individuals affected, as reported by Memorial Sloan Kettering Cancer Center to HHS, multiplied by IBM's customer-PII cost per record (Cost of a Data Breach 2025 Figure 6 and the 2026 edition). No cost has been disclosed by the entity for this filing; the figure is a planning estimate, not a fact about the breach. IBM's per-record figures come from mid-volume breaches and IBM cautions against applying them to breaches involving millions of records; the site's per-record page explains where the multiplication holds and where it breaks down.
Context: IBM's average cost of a healthcare breach is $6.64M in the 2026 report ($7.42M in 2025); the global average across all sectors was $4.44M in 2025.
Cost per record: method and limits / Healthcare breach cost, IBM 2026
Section F.6 / Notification clock
New York statute and the HIPAA rule
State notification statute
New York: N.Y. Gen. Bus. Law 899-aa
amended by the SHIELD Act
- Notice to individuals
- In the most expedient time possible and without unreasonable delay, no later than 30 days after discovery
- Attorney general threshold
- All breaches (AG, Dept. of State, State Police) (Aligned with timing and content of individual notices)
- Private right of action
- Limited: Actual damages only; no statutory damages and no attorney-fee recovery; enforced primarily by the AG
- Penalty
- Greater of $5,000 or $20 per failed notification, capped at $250,000; safeguard violations up to $5,000 each
The HIPAA Breach Notification Rule runs alongside the state statute: notice to affected individuals and to HHS without unreasonable delay and no later than 60 days after discovery.
Section F.7 / Peer filings
New York filings closest in size
Neighbours by size rank among New York filings in 2021, topped up from other years where 2021 has too few. Filings of 10,000 or more link to their own page.
| Covered entity | Type | Individuals | Submitted | Breach type | Location | BA |
|---|---|---|---|---|---|---|
| Rehabilitation Support Services, Inc. | Healthcare Provider | 23,907 | 10 Sep 2021 | |||
| Welfare, Pension and Annuity Funds of Local No. ONE, I.A.T.S.E. | Health Plan | 20,579 | 21 Dec 2021 | |||
| Faxton St. Luke's Healthcare | Healthcare Provider | 17,656 | 26 Apr 2021 | |||
| Samaritan Daytop Village, Inc. | Healthcare Provider | 15,459 | 26 Oct 2021 |
Index / Companion schedules
13 HHS breach register
→Hub: every filing, by state, year and entity.
04 Biggest breaches
→Mega-breaches with primary-source cost figures.
Industry / Healthcare
→IBM 2026: $6.64M average, 13 years at #1.
Regulation / HIPAA penalties
→OCR enforcement tiers and the 60-day rule.
11 50-state laws
→Deadline, AG threshold and penalties per state.
Cost / Per record
→Where the per-record model is reliable.
Provenance
Source: U.S. Department of Health and Human Services, Office for Civil Rights, Breach Portal (breaches affecting 500 or more individuals), retrieved 2026-08-28. Public domain. Individuals affected and dates as reported by the covered entity.
Portal: ocrportal.hhs.gov breach report. Statutory basis: HITECH Act section 13402(e)(4): the Secretary must post a list of breaches of unsecured protected health information affecting 500 or more individuals. Breaches affecting fewer than 500 individuals are reported to OCR annually and are not posted, so they are not on this register. Status wording follows the portal's two tabs ("Cases Currently Under Investigation" and "Archive") as of 28 August 2026; a filing moves to the archive when OCR closes the case. Modelled costs on this site are a method applied to the reported count, using IBM Cost of a Data Breach per-record figures, and are never a cost disclosed by the entity. This row: hhs-breach-archive__2026-08-28.csv, export row 3298.
Corrections: if you represent a listed entity and the portal row has been amended, email [email protected] with the portal entry and we will re-pull the export.