SINGAPORE: "Human error" and inadequate quality control contributed to the inaccurate test results that wrongly classified patients at Khoo Teck Puat Hospital (KTPH) as having a more aggressive form of breast cancer, a review committee said on Monday (May 3).
At least 200 patients were affected by the errors, which took place over eight years at KTPH's Department of Laboratory Medicine, Anatomic Pathology Section. About half of them may have received unnecessary treatment.
The errors involved unusually high HER2 positive rates for breast cancer patients. HER2, or Human Epidermal Growth Factor Receptor 2, is a gene that controls how a healthy cell grows, divides and repairs itself.
HER2-positive breast cancers tend to be more aggressive than other types of breast cancer, according to the Mayo Clinic.
An independent investigation by the National Health Group (NHG) Review Committee revealed that inadequate quality control contributed to a failure to detect the error early. Five members of KTPH's management and staff were identified for "not adequately performing their duties and responsibilities", and were penalised.
The committee found that inaccurate HER2 positive rates were caused by a "suboptimal HER2 staining protocol" used by the HER2 immunohistochemistry section.
"The suboptimal HER2 staining protocol was caused by human error when establishing the protocol. This led to over-staining of slides, which affected the interpretation of the slides, resulting in a higher than usual HER2 positive rate," said the NHG.
"The calibration error was not discovered due to a failure to conduct rigorous checks at the point when the protocol was established."
Investigations by the committee also showed "inadequacies" in the section's quality control.
The review committee found that the deviation of HER2-positive rates from international benchmarks was noted earlier on during the laboratory's regular monitoring.
KTPH's HER2 testing section checked the accuracy of the reading of slides containing the patient samples at that time, and attributed the deviation to "differences in patient population", said NHG.
It did not recheck the accuracy of the laboratory's staining protocol, said NHG.
"Staff from KTPH’s HER2 IHC section failed to perform quality control checks properly, including monitoring and properly analysing the HER2 positive trend closely over time, which affected the interpretation of the over-stained slides and a delay in detection of the error," said the group.
This inadequate quality control and assurances contributed to the failure to detect the overstaining issue early and over the years, when tests were conducted.
An internal review was conducted last year when clinicians reviewing breast cancer cases noticed the unusually high positive rate, it said.
The review committee, comprising experts from the healthcare industry, was conducting a review of KTPH's HER2 testing processes from Jan 1, 2012 – the year it started testing patients for the gene – to Oct 26, 2020.
READ: About 90 breast cancer patients may have received unnecessary treatment after inaccurate classification of 180 cases: KTPH
PATIENTS TO RECEIVE COUNSELLING, FIVE STAFF DISCIPLINED
A disciplinary committee was convened by the NHG Board in March this year after the completion of the Board of Inquiry's deliberations.
Five people, comprising both KTPH management and staff members, were identified for not adequately performing their duties, leading to serious lapses, said NHG.
They were given penalties including cessation of employment, financial penalty and a stern warning. Counselling, retraining and "re-education" are being conducted, added the group.
Apologising for the lapses, Associate Professor Pek Wee Yang, chairman of the hospital's medical board, said KTPH views the incident "very seriously" and will provide psychological counselling to the affected patients.
"We have reached out to all affected patients to offer our support, and we give the assurance that we will look into the appropriate compensation for each individual patient," he said.
Senior Minister of State for Health Koh Poh Koon earlier told Parliament that costs incurred by patients due to unnecessary treatment will be fully refunded.
To prevent future similar incidents, the review committee made recommendations for improvement including in the processes and practices governing the use of laboratory-developed tests, quality control and assurances, governance and oversight, staff training, as well as education and professional competencies.
These recommendations seek to prevent future occurrence of similar incidents, and include:
- Proper selection of the correct assay optimisation protocol, and improving the checking process to confirm the selected protocol
- Strengthening the Quality Control (QC) and Quality Assurance processes for the HER2 IHC section, and designating staff with the expertise to oversee the programme
- Close monitoring and auditing of processes and results using best industry practices and international benchmarking
- Retraining, re-educating and upgrading competencies to reinforce professional technical knowledge and skills
NHG has formed an implementation committee to ensure that KTPH implements all the recommendations.
"We are determined to set things right to regain the trust and confidence of our patients. We will expeditiously rectify all gaps in our processes in the laboratory. Moving forward, we will ensure strict adherence to industry's best practices and international benchmarks," said Assoc Prof Pek.
The review committee has submitted the report of its independent investigation to the Ministry of Health, NHG's group CEO Professor Philip Choo and the NHG's Board Risk Committee.
"On behalf of NHG, we deeply regret the incident," said Prof Choo. "Patient care and safety will always remain our top priority."