A child cancer specialist has admitted sexually abusing boys in his care.
Myles Bradbury, a paediatric haematologist at Addenbrooke's Hospital in Cambridge, committed sexual offences against boys aged 8 to 17 between 2009 and 2013, Cambridge Crown Court heard.
The 41-year-old from Herringswell, Suffolk, pleaded guilty to 25 offences including sexual assault and the making of more than 16,000 indecent images.
He was bailed and is due to be sentenced at a later date.
As he left court, Bradbury told reporters "I'm so sorry" and refused to answer further questions.
The offences involved 18 complainants, prosecutor John Farmer said.
The court heard the blood cancer specialist had worked at the hospital for five years.
He was suspended after a complaint about his behaviour in November last year.
A spokesman for Addenbrooke's Hospital said Bradbury no longer worked for Cambridgeshire University Hospitals Trust.
In total he pleaded guilty to six counts of sexual assault and 13 counts of engaging in sexual activity with a child.
Bradbury also admitted three counts of causing or inciting a child to engage in sexual activity, one count of voyeurism and two counts of making indecent images of a child.
Dr Myles Bradbury
- Graduated with an MB ChB degree from the University of Birmingham in 1996
- Registered as a haematologist in 2007
- Was a member of the Royal College of Paediatrics and Child Health, responsible for the training of postgraduate doctors, until February
- Was the clinical trials lead for paediatric haematology and oncology at Addenbrooke's
- Had access to 128 young people between April 2012 and March 2013 during a study of malignancy
- In leukaemia trials he had access to patients aged between one and 25 years old
- Has been involved in other studies including the genetic analysis of inherited platelet disorders
Sources: General Medical Council, Cambridge University Hospitals NHS Foundation Trust, Royal College of Paediatrics and Child Health
He pleaded not guilty to a count of sexual activity with a child and a count of sexual assault, which Judge Gareth Hawkesworth said would likely remain on file.
The judge said the doctor could expect a "substantial" custodial sentence and would have to sign the sex offenders register.
Addenbrooke's Hospital said it had contacted the families of the children it was aware of that Dr Bradbury saw. It has set up a helpline for anyone else affected by the case.
Dr Keith McNeil, its chief executive, said: "Our most abject and sincere apologies go out to any and all of our patients and their families who are affected by this in any way.
"There is a very ancient and sacred trust that exists between a doctor and his patients, and quite frankly, it sickens me to think that trust has been breached."
Chief nurse Ann-Marie Ingle, said: "His cold and calculating abuse of trust has deeply shocked us all, including staff who worked alongside him to care for these vulnerable and sick children.
"As soon as we were alerted, we took immediate action to suspend him from clinical practice."
Cambridgeshire Police said "there are likely to be more victims" and asked affected people to call the hospital's helpline.
Det Sgt Shane Fasey, said: "Bradbury's offences were an appalling breach of trust committed against vulnerable victims who had been placed in his care.
"The families believed the boys were in his safe hands but they were actually being abused by Bradbury, who carried out examinations purely for his own sexual gratification and with no medical justification whatsoever."