The Health Ministry announced Sunday that a flaw was discovered in diagnostic kits manufactured by Roche for detecting hormone receptors in cancerous tumors, mainly in cases of breast cancer and reproductive system tumors.
The issue could mean that some patients, particularly women, did not receive anti-hormonal therapy that might have benefited them. Roche notified medical institutions of the defect in late August, but the Health Ministry only now made the issue public.
So far, the company and the ministry have not received reports of direct harm to patients, but officials acknowledge it is possible that some women who were eligible for hormonal therapy may have been treated instead with chemotherapy, a harsher and more toxic regimen.
Roche has ordered an immediate halt to the use of the affected test kits and instructed labs to destroy existing stock. The ministry has since directed all pathology laboratories to review cases where the faulty kits were used and retest samples if necessary.
'Some patients may not have received the right treatment'
“The concern is mainly that patients who could have received a certain therapy perhaps didn’t get it,” said Dr. Hagar Mizrahi, head of the medical division at the Health Ministry, in a briefing to reporters.
She clarified that the test does not diagnose cancer itself but rather determines whether hormone receptors—such as estrogen (ER) and progesterone (PR)—are present in tumor cells, information critical for tailoring treatment plans.
According to Roche’s estimates, about 300 patients underwent testing using the defective batches. “We’re not certain about the exact number, so we’ve asked all laboratories to map the affected cases and report back,” Dr. Mizrahi said.
When asked why the public was informed only now, Dr. Mizrahi said the ministry needed time to formulate a clear action plan: “It was important to balance transparency with responsibility. We didn’t want to cause panic without providing solutions. The idea was to say, ‘Yes, there’s a problem—but there’s also a solution.’”
The ministry, she added, has since held consultations with pathologists and oncology experts to determine the safest way to handle the issue and ensure no patients fall through the cracks.
What went wrong with the test
The ER/PR receptor test is routinely performed on biopsy or surgical tissue samples to help determine the tumor’s characteristics and guide treatment decisions. It uses immunohistochemical (IHC) staining, a lab method that detects hormone receptors on tumor cells.
“The malfunction weakened the staining intensity,” Dr. Mizrahi explained. “For example, a tumor that should have received a score of 3 might have been scored 2 or lower. That could affect treatment decisions.”
While other clinical factors—such as disease stage, patient age, and metastasis—are also considered, the receptor test plays a key role in deciding whether anti-hormonal drugs like tamoxifen are prescribed. These treatments are often less toxic than chemotherapy, especially for older women or those with preexisting conditions.
Following consultations with the Israeli Society of Pathologists and the Israeli Breast Oncology Association, the Health Ministry concluded that even minor underestimation in receptor levels could influence clinical judgment—potentially leading to unnecessary chemotherapy or missed hormonal treatment.
Labs have been instructed to re-examine all cases where the questionable test kits were used and results did not show the highest receptor level. If needed, samples will be retested, and physicians will update patients accordingly. Each lab must submit a summary report within a month.
Roche stated that repeat testing of negative samples is not mandatory but left the decision to the discretion of medical professionals.
Dr. Mizrahi assured the public that patients do not need to reach out proactively: “This process will take time, but patients will be contacted directly if their samples are retested or if there is any change in their treatment recommendations,” she said.