A problem with a piece of equipment may have resulted in 25 patients receiving flawed radiation treatment for cervical cancer, a southern Ontario hospital said Thursday.

Hamilton Health Sciences, home to the Juravinski Cancer Centre, said the issues relate to women who received a treatment known as brachytherapy in 2017 and 2018.

While only a small number of patients may have been impacted by the equipment issue -- which involved a guide tube that was longer than specified -- the hospital's vice-president for oncology and palliative care acknowledged the impact could be serious.

Dr. Ralph Meyer said patients may have had radiation applied to healthy tissue rather than the tumour the treatment was supposed to target, leading either to untreated cancer or damage to parts of the vagina.

While he said the hospital is still trying to determine whether any of the 25 affected women have sustained such effects, he said the mere possibility leaves hospital staff with the sense that they let patients down.

"It's not who we are," Meyer said in a telephone interview. "Given that it's occurred, we first off need to deal with the patients. We then need to ensure our staff are in a good place to advance our program, and we need to understand better the root causes of what occurred."

Meyer said brachytherapy, a type of external beam radiation, is used to treat different types of cancer including malignant tumours on the lungs, uterus or esophagus. He said only patients who received brachytherapy for cervical cancer are impacted by the discovery of the faulty tube, which was made in late November.

Technicians discovered that a guide tube that helps direct the radiation source to the area targeted for treatment was four centimetres longer than it had been labelled, Meyer said. The result, he said, was that radiation may have been applied to the wrong area, possibly leaving the tumour untouched and damaging previously healthy tissue.

He said the hospital began responding to the discovery as soon as it was made, focusing on contacting potentially impacted patients before announcing the incident publicly.

"There are patients who have been upset, understandably so, and reacted with a lot of concern," he said, adding those who received treatment more recently are at a higher risk of experiencing adverse effects down the line.

Meyer said the hospital has apologized to all 25 patients and established plans to monitor their health in the coming months. He said adverse effects may take some time to surface, adding it may not be possible to determine if any symptoms can be directly linked back to the equipment flaw.

Meyer said the hospital has also taken steps to prevent similar incidents in the future.

Brachytherapy for cervical cancer has been temporarily halted, he said, adding future patients in need of that specific treatment are currently being referred to a cancer care centre in London, Ont.

While other forms of brachytherapy are still being conducted at Hamilton Health Sciences, Meyer said the hospital is hiring external experts to conduct a review of its entire radiation program. The faulty equipment has also been replaced, he added.

"When an issue like this occurs, it's not about individual blame fault," he said. "These are systems issues ... Our community needs to be confident we're giving high-quality care."