A female GP who underwent a mastectomy was "cancer-phobic", a court has heard.
Prosecutors said surgeon Ian Paterson is accused of carrying out the "quite unnecessary" measure on Rosemary Platt.
Nottingham Crown Court has previously heard Dr Platt was "anxious" about her health and under the impression she already had cancer.
Mr Paterson, 59, denies 20 counts of wounding with intent against nine women and one man relating to procedures he carried out between 1997 and 2011.
The breast surgeon, of Castle Mill Lane, Ashley, Altrincham, Greater Manchester, was employed by Heart of England NHS Trust and also practised at Spire Healthcare.
He said the mastectomy on Dr Platt "was carried out to prevent cancer, not to treat it".
Mr Paterson said he knew from a psychiatrist's report, that the GP had "a cancer phobia" and the "way to protect herself" was "she would do everything she could to maximise her protection".
The breast surgeon said he would be prepared to "over-treat" her as if her problems were "at the black end of the spectrum" owing to her fears.
"If I had been desperate to play on this lady's anxiety, I'm sure I could have persuaded her to have another operation but I did not," he said.
Dr Platt previously told the jury she "left her GP hat at the door" and trusted the advice given to her by the consultant to go under the knife after discovering the growths in her right breast.
Four months later, she had another operation on her left breast which the prosecution claim was unlawful.
The trial continues.