Mr Foster, who was engaged to be married, had testicular cancer and was told by doctors his chances of survival would increase because of the trial.
However, he died five months later after his lungs failed.
It was revealed today that his family has won damages thought to be in excess of £300,000. Now his mother Colleen, wants the General Medical Council to act after claiming he was 'slowly poisoned to death.'
It is understood that Mrs Foster wants a case brought against Dr Stephen Harland who was in charge of his care and led the government-funded trial.
If the GMC investigates the concerns of the family, from Waltham Abbey in Essex, it must then decide whether to refer the doctor to a fitness to practise panel or take no further action.
A second testicular cancer patient died during the trial, which was carried out at several hospitals. Gareth Kingdon, 39, from Tunbridge Wells, father of a seven-month-old boy, developed fatal side effects to the drug bleomycin.
His family said they believe he might still be alive if doctors at the Royal Marsden had noticed his reaction.
An inquest into Mr Foster’s death revealed that doctors and nurses should have recognised warning signs before he was given a final dose.
The coroner ruled he died as a result of lung damage caused by an overdose of bleomycin, and found that instructions for the trial had been wrongly set up on the electronic prescribing system at UCLH.
Mr Foster, who planned to marry his fiancée Paula Collins, joined the trial in June 2007 after being diagnosed with cancer. Doctors assured him his chances of survival would increase. Months later, his lungs began to fail and he died that October.
A second UCLH patient affected by the error survived. Mark Bowman, the Foster family’s solicitor, said the case highlighted a 'systemic failure' in the way the trial was set up, run and monitored.
Bleomycin is already used to treat testicular cancer. The trial was examining whether a combination of five chemotherapy drugs, including bleomycin, was better at treating the condition than the standard treatment of three drugs. UCLH today confirmed that a settlement has been reached with the Foster family.
The hospital said: 'UCLH co-operated fully with the coroner who concluded that death occurred as a result of an accidental health care event and that following a full investigation, the trust had taken measures to prevent any recurrence.
'We would not comment on a family action with a regulatory body. UCLH would once again wish to extend its condolences to Mr Foster’s family.'
The Medical Research Council, which ran the trials, admitted an error had been made but said it was not to blame for Mr Foster’s death. Dr Harland could not be reached for comment and the GMC declined to comment.