Fort Myers, Florida.-based 21st Century Oncology, which operates 145 centers across the United States and 36 in Latin America, said it is investigating a breach of its computer network that could affect 2.2 million of its former and current patients. The news comes as the provider on Thursday also agreed to settle a billing fraud case for $34.7 million.

"21st Century Oncology is committed to maintaining the privacy and security of our patients' personal information, the company wrote in a notice posted on its website. "Regrettably, this notice is to inform you of an incident involving some of that information."

[Also: Hollywood Presbyterian gives in to hackers]

The FBI had notified the company of a possible breach back in November 2015, 21st Century Oncology executives said.

"The FBI asked that we delay notification or public announcement of the incident until now so as not to interfere with its investigation," they said. "We have no indication that the information has been misused in any way; however, out of an abundance of caution, we are notifying the affected patients and offering them a free one-year credit protection services."

[Also: See our big gallery of HIMSS16 photos]

On Thursday The U.S. Department of Justice announced that the providers would pay $34.7 million to settle allegations that they performed and billed for procedures that were not medically necessary.

The settlement relates to use of a medical procedure – called the Gamma function – to measure the exit dose of radiation from a patient after receiving radiation treatment. The Justice Department alleged that the defendants knowingly and improperly billed for this procedure under circumstances where the procedure served no medically appropriate purpose.

"Today's settlement demonstrates our unwavering commitment to protect the Medicare trust fund against unscrupulous providers," said Principal Deputy Assistant Attorney General Benjamin C. Mizer, head of the Justice Department's Civil Division, in a statement on the Department of Justice website.

Twitter: @HealthITNews