Healthtech company Novocure says the data of an undisclosed number of employees and more than 1,400 U.S. cancer patients has been exposed in a mid-August cyberattack.

Novocure is a global oncology company with more than 1,300 employees and operations in North America, Europe, the Middle East, and Asia, known for inventing and commercializing Tumor Treating Fields (TTFields), a non-invasive electromagnetic field therapy for cancer tumors.

The Company disclosed in a filing with the U.S. Securities and Exchange Commission (SEC) that it discovered the incident after unauthorized access to some of its information systems in mid-August.

According to a follow-up investigation, the attackers accessed over 1,400 U.S. patient records with ID numbers, but those records didn't contain patient names or other identifying data. However, for fewer than 50 other patients in the western U.S, the threat actors accessed identifying information and general contact information for healthcare providers.

The data breach also exposed contact information for an undisclosed number of Novocure employees, including job titles and phone numbers.