Quest Diagnostics Reports Theft of Patient Data from Quanum System

Quest Diagnostics confirmed a cyberattack on its lab ordering platform.

The company filed an 8-K with the Securities and Exchange Commission on Wednesday, October 23, 2026. The filing states that hackers accessed Quanum, a system used by healthcare providers to order tests and manage billing.

Quest said the unauthorized access included certain patient records. The company has notified law enforcement and is currently investigating the incident. A security notice on its website confirms that protected health information was taken. This includes personal information and patient records, though the specific types of data stolen are still being determined.

The company has not released the total number of affected patients or healthcare customers. It has also not disclosed when the breach began or if a hacking group has contacted it with ransom demands. Amanda Rivera, a Quest spokesperson, directed media inquiries to the security notice instead of answering questions directly.

Quanum is used by approximately 500,000 clinicians across thousands of locations in North America. While the total volume of stored records is unclear, a 2026 case study on Quest's website describes one health system with more than 6 million patients. That single system holds hundreds of millions of related medical documents and charts.

This is the second major data breach for Quest in ten years. In 2019, the company lost 11.9 million patient records following an attack on a third-party billing company.

Healthcare firms have faced frequent cyber incidents this year. An attack in March wiped employee devices at Stryker. In August, a hack at Boston Scientific forced its network offline for weeks. Other large breaches this year affected CareCloud, Craneware, and McKesson. Criminals often target these firms to steal data and demand ransom payments.