SINGAPORE, Dec 13 — About 180 breast cancer patients over the past eight years may have been incorrectly diagnosed with a type of malfunctioning gene, and half of them may have received unnecessary treatment, Khoo Teck Puat Hospital said on Friday.

In a media release, the hospital said preliminary investigations indicated this had resulted from an incorrect process in its laboratory in relation to tests for human epidermal growth factor receptor 2 (HER2), which is a gene determining how a healthy cell grows.

An HER2 positive test result suggests that the gene is malfunctioning, leading to the uncontrolled growth of cells, and affects how a patient is treated, usually with a drug called Herceptin, it said.

The hospital said that based on initial estimates, about 180 breast cancer patients may have to be reclassified from HER2 positive to HER2 negative and about half of them may have received unnecessary treatment.

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Common side-effects of Herceptin (chemical name trastuzumab) include diarrhoea, chills and fever, and about 3 to 4 per cent may also experience heart problems.

The treatment regime of affected patients will be reviewed by their oncologists, the hospital said.

The immunohistochemistry HER2 test is conducted on patients who have breast cancer to classify the patient’s HER2 status and help guide treatment. It does not diagnose whether a person has cancer.

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On Nov 19, the hospital was informed by its laboratory that the tests were producing higher-than-expected rates of positive results. Preliminary investigations by the laboratory suggested that the incorrect staining process for the test had produced inaccurate HER2 results.

KTPH then reported this incident to the National Healthcare Group on Nov 22, and to the Ministry of Health on Nov 24.Since the issue was discovered, the hospital said that it has investigated the extent of the issue and identified all the affected patients. Their samples, dating back to 2012 when HER2 testing started at the hospital, have all been sent to various external laboratories to expedite re-testing for HER2.To ensure patient safety, the laboratory has also stopped in-house immunohistochemistry HER2 testing, KTPH said.

Chew Kwee Tiang, the hospital’s chief executive officer, said: “I would like to convey my deepest apologies to all the affected patients, their families and their treating oncologists. I am very sorry that they have to go through this. We will provide all the necessary support and assistance, and will do our best to take care of them.

“We treat this incident very seriously and will take all the necessary steps to ensure this does not happen again.”

Patients who have any related queries may contact the hospital at this dedicated hotline: 6602-3333.

MOH takes 'serious view' of incident

In a statement also released on Friday, MOH said that it is taking “a serious view of this incident” and is working with the hospital to review its processes to prevent a recurrence of the incident.

MOH added that as a safety precaution to ensure that other laboratory tests do not face the same issue, it has asked Khoo Teck Puat Hospital to review other laboratory protocols beyond those for HER2 tests.

It has also alerted other healthcare institutions to review their laboratory protocols in light of this incident.

MOH said it is also closely monitoring Khoo Teck Puat Hospital’s response in ensuring affected patients receive appropriate support and intervention.

“Acute hospitals such as Khoo Teck Puat Hospital are subject to Private Hospitals and Medical Clinics Regulations to ensure that their laboratory facilities, processes, quality measures and internal process to identify, investigate and resolve laboratory issues are in place for the safety of the patients and staff working in the laboratory.

“Appropriate enforcement action will be taken if a breach of protocol is found,” said MOH. — TODAY