Twenty-two cancer patients could have been harmed after their care was not properly followed up, a hospital trust has admitted.
Ashford and St Peter's Hospitals NHS Foundation Trust said treatment plans for 22 patients were not reviewed in a timely way "which has the potential to cause harm".
The trust, which operates two hospital sites in Surrey, said the patients "were not appropriately followed up".
But "a number did not suffer any adverse outcome", the trust concluded following investigations into each of the cases.
Of the 22, three patients have either died or are terminally ill. But the trust does not believe that at least two of these cases are attributable to delays in care.
Some of the cases date back to 2011, according to a statement from the trust.
"Over the last few years, Ashford and St Peter's Hospitals NHS Foundation Trust has reported 22 incidents where patients being treated for cancer were not appropriately followed up," the trust said in a statement.
"This means that their treatment plans were not reviewed in a timely way, which has the potential to cause harm.
"Of these 22 individual cases, some of which date back to 2011, three patients have died or are receiving palliative care.
"It is always difficult to determine exactly what level of harm may have been caused by a delay and whilst we cannot disclose details of individual patients, in at least two of these three cases we know this is not directly attributable to the delay in their care.
"In addition, we know that of these 22 individuals, a number did not suffer any adverse outcome but are reported as serious incidents due to the potential harm that could result from delay.
"Each of these incidents has been thoroughly investigated by the trust, in close liaison with the patient and their family, and we have openly shared the findings of our investigations and the actions we are taking to make improvements with them.
"There are many different and complex reasons why a patient may become lost to follow-up but the reliance on paper and notification forms to support patients and to administrate their pathways is not sufficiently robust to ensure it is fool-proof."
It said the trust launched a new initiative last year to review and improve the administrative procedures for cancer patients.
It added that it operates a "pro-active safety culture" where staff are encouraged to report incidents.
The organisation caters for 380,000 people in north-west Surrey and parts of Hounslow.