Butcher surgeon Ian Paterson could have hundreds more victims after 1,500 other patients were found on an old computer database.
Paterson is serving a 20-year sentence for carrying out unnecessary operations.
He was jailed in 2017 on 17 counts of wounding with intent.
Following a review, Spire Healthcare is set to contact 1,500 patients.
They were discovered on an IT system used from 1993 to the early 2000s when he was operating at Spire hospitals in the West Midlands.
As many as 5,500 patients in the private sector have had their operations checked. The new cohort will also be offered a review.
Dr Cathy Cale, Spire Healthcare’s group medical director, said: “We’ve been absolutely committed to identifying, tracking down and contacting all living patients of Ian Paterson.
"Understandably, it’s not been easy to navigate our way around some of these data, which are more than 20 years old.
“Now we have been able to extract new patient information, we will write to those patients in the next few weeks to offer any support they need.
“We are very sorry for the significant distress and harm suffered by patients treated by Ian Paterson.”
The consultant breast surgeon was employed by the Heart of England NHS Foundation Trust but had practising privileges in the independent sector at Spire Parkway in Solihull and Spire Little Aston in Birmingham when he was suspended in 2011.
An independent inquiry, published in February 2020, found “patients were let down over many years” by the NHS and private hospitals.
