Editor's note: The headline has been edited to reflect the statement by SMS Koh Poh Koon more accurately. 

On Dec. 11, Khoo Teck Puat Hospital (KTPH) released a statement announcing that over an 8-year period, approximately 90 breast cancer patients may have had received unnecessary treatment due to a misdiagnosis of a malfunctioning gene.

In response to parliamentary questions on the incident, Senior Minister of State for Health Koh Poh Koon said that the Ministry of Health (MOH) has been working closely with KTPH to ensure that the affected patients are provided adequate support.

"KTPH is also ready to provide any clinical and financial support to the affected patients including on-going or follow-up treatment, if any, which may be needed as a result of over-treatment," said Koh.

Koh added that since December 23, 2020, around 200 patients were found to be misdiagnosed with this malfunctioning gene.

Koh also said that KTPH is reviewing the bills of affected patients, and the portion of the bills which arose from unnecessary treatment will be fully refunded.

Non-Constituency Member of Parliament Hazel Poa asked in a supplementary question if a lifetime of free healthcare is being considered as a possible form of compensation.

Koh said that any costs related to treatment or tests due to the wrong results will be refunded.

"But to then say that this translates to a lifetime of compensation, I think that will be a little bit too far thing to stretch, because most of the complications, if any [...] are transient. Diarrhoea, fever, or chills, they do not have long term consequences. They are not long-lasting. And I think we have to take that in the current context of medical treatment," said Koh.

200 patients reclassified

The inaccurate tests results have to do with the Human Epidermal Growth Factor Receptor 2 (HER2) — a gene that controls how a healthy cell grows, divides and repairs itself.

A HER2 positive test result suggests that the HER2 gene is malfunctioning, making too many copies of itself, overproducing HER2 proteins and leading to uncontrolled growth of cells.

Koh said in his response: "As at December 23, 2020, 200 patients have been reclassified from HER2 positive to HER2 negative. Of these 8 patients were treated at private hospitals and 192 patients at Government. 8 patients are still pending retests."

"Joint care teams have been formed...to review the individual care plans for these affected patients based on the change in HER2 status."

In a supplementary question, Member of Parliament (MP) Tan Wu Meng asked if the authorities will bear in mind that patients who undergo unnecessary treatment had to make recurrent trips to the clinic, which might have implications on their personal finance and job security.

Koh said that patients who were subjected to unnecessary treatment will receive a more compassionate approach by KTPH, and their managing oncologists and doctors to help these patients overcome the disease and their anxieties.

Koh added: "But I must also say that in this situation, where the issue is one more of a false positive, it does mean that some patients would have perhaps over-treatment."

"But I think it's probably a preferred thing than to have under-treatment, especially when you have cancer."

Koh said that the wrongly-classified patients actually had a "better prognosis than those who are HER2 positive." He said:

"So I think, on the overall, it is not necessarily a bad thing for the patients who have actually reclassified as HER2 negative on testing."

Errors are inherent in any lab test

MP Cheryl Chan asked as a supplementary question why during the recurrent visits with their doctors was the wrong classification not picked up.

Koh said that inherent in any laboratory test there is always a chance of false positivity and false negativity.

"Immunohistochemistry test is fairly notorious for having this kind of risk, because as I said, it is semi-quantitative," added Koh. He said that if any part of the process is not done optimally, the kind of picture that comes out might not be quite the same.

Koh said that the false positive rate for this type of test is about six per cent or less, and that it can never be zero. However, Koh said that a review can only be triggered when a sufficient number of cases is accumulated over years, and researchers can say that the false positive rate is more than six per cent.

Koh also said that the National Healthcare Group has convened an independent review committee to conduct a thorough evaluation of the incident to better understand the lapses that have occurred.

Top image adapted from Gov.sg/YouTube and KTPH/Facebook.