A patient has died after being mistakenly taken off a surgical waiting list for endoscopy screening in 2005.
The patient was one of 49 South Canterbury District Health Board patients due to have the procedure whose names were incorrectly removed from the list.
The procedure uses a camera fed into the patient's body via a tube to record images that can be used to help confirm a diagnosis for illnesses such as cancer.
DHB chief executive Chris Fleming says patients who had been due for their five-yearly screening for cancer were low-risk patients with a family history of cancer.
Mr Fleming says the board has since contacted 28 of the patients taken off the list and asked them to come in for screening.
Seventeen of them no longer needed screening and four others had since died, but only one of those deaths might conceivably have been linked to the error, he says.
Mr Fleming says the board has changed its processes so that patients' GPs, who see them more regularly, manage their routine screening appointments.
The local branch of the Cancer Society is urging patients to get involved in managing their own case files and appointments.
The chief executive of the Cancer Society for Canterbury and the West Coast, Liz Chesterman, says hospital systems are prone to mistakes and patients should be pro-active about checking their hospital appointments.