A breast surgeon "invented or exaggerated" cancer risks to carry out "unnecessary" operations, a jury heard.
Ian Paterson, 59, of Altrincham, denies 20 counts of wounding with intent against nine women and one man.
Prosecutor Julian Christopher told Nottingham Crown Court some patients had developed mental health problems as a result of their treatment.
The procedures took place at the Heart of England NHS Trust and Spire Healthcare between 1997 and 2011.
The trial is expected to last 10 weeks.