Quest Diagnostics Reports Cyberattack on Patient Test Results System

The diagnostic laboratory company disclosed the incident in a filing with the US Securities and Exchange Commission (SEC) on Thursday, October 22, 2026.

Quest Diagnostics has reported unauthorized access to its Quanum LSM system, raising concerns that certain patient records may have been compromised. The diagnostic laboratory company disclosed the incident in a filing with the US Securities and Exchange Commission (SEC) on Thursday, October 22, 2026.

According to the filing, Quest became aware of the unauthorized access on October 21. The Quanum LSM system is used by certain clients to place test orders, receive results, and look up patient test information. The company believes an unauthorized party gained access to certain patient records but has not disclosed how many records may have been affected.

Quest is investigating the incident with assistance from external cybersecurity experts and has notified federal law enforcement authorities.

The company said the incident has not materially disrupted its business operations or its ability to serve patients. Further details about the scope of the breach and the potential exposure of patient information have not been disclosed.

MedTech Cyberattacks Raise Data Security Concerns

The incident adds to a growing number of cybersecurity events affecting the medical technology and life sciences industries in 2026.

Quest joins several other companies, including Novocure, Boston Scientific, Medtronic, Stryker, Abbott and iRhythm, that have experienced cyber incidents this year. In a separate incident, Novocure reported a cyberattack involving the exposure of patient data.

Cyberattacks targeting healthcare organizations can put sensitive patient information at risk and disrupt systems used to manage diagnostic testing and clinical services.

Quest Diagnostics Reports $3.1 Bn in Q3 Revenue

The cybersecurity disclosure came on the same day Quest Diagnostics reported its third-quarter financial results for 2026.

The company recorded revenue of $3.1 billion, representing a 10% increase year over year. Jim Davis, chairperson, CEO, and president of Quest Diagnostics, said the company was raising its revenue and earnings per share (EPS) guidance for the full year.

Quest has not indicated that the cybersecurity incident materially affected its reported financial performance or operations.

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