A novel semi-dry dot-blot (SDB) kit showed high sensitivity and specificity for detecting macrometastases in patients with breast cancer, according to research presented at the 2024 San Antonio Breast Cancer Symposium.
The kit uses the SDB method and an anti-CK19 antibody to identify macrometastases. Ryota Otsubo, MD, PhD, Yuki Hara, MD, and colleagues evaluated the kit’s performance in combination with a device that automatically reads the kit’s results.
Physician’s Weekly spoke with Dr. Otsubo and Dr. Hara about their research and how they anticipate the SDB kit will be applied in clinical settings.
What was the purpose of your prospective, multicenter study?
We conducted a prospective, multicenter study to validate the SDB kit for detecting macrometastases in patients with breast cancer. We plan to make the kit commercially available in the near future.
How did the performance of the SDB kit compare with traditional histological examinations in detecting lymph node metastases?
Compared with traditional, permanent histological examination, the SDB kit performed excellently for patients with breast cancer without primary systemic therapy, with 94.7% sensitivity, 98.3% specificity, and 97.9% overall agreement. The kit also performed excellently for those who received primary systemic therapy, with 91.7% sensitivity, 100% specificity, and 99.0% overall agreement.
What advantages did the automatic reader provide?
We used to evaluate the reaction of the kit with the naked eye, but it was difficult to provide an accurate evaluation for small macrometastases. The automatic reader can provide an accurate evaluation of the kit’s reaction so we can distinguish macrometastases, which are important for decision-making whether we perform axillary lymph node dissection or not. The automatic reader will be suitable for clinical application because it offers an objective evaluation.
How might the use of the SDB kit influence intraoperative decision-making and surgical outcomes for patients with metastatic breast cancer?
The performance of the SDB kit was better than that of the intraoperative pathological examination, especially in sensitivity. If the SDB kit is used in combination with pathological examination, fully or partially, it can help provide more accurate intraoperative diagnosis and reduce pathologists’ work burden. If the SDB kit is used without pathological examination, it still can reduce pathologists’ work burden, and it might facilitate diagnosis for lymph node metastases at institutions without pathologists.
What are the next steps for refining or scaling the SDB kit for widespread clinical application?
For widespread clinical application, we plan to set “the gray zone” around the cutoff line to help clinicians decide when to combine intraoperative pathology or omit it, because obvious high and low reactions are reliable for distinguishing macrometastases, which will reduce pathologists’ work burden. We also need to perform international clinical trials, especially in countries in which there is an insufficient number of pathologists, and make additional procedures for CK19-negative breast cancer, whose incidence is about 1.8%.
Is there anything else you would like to add?
The SDB kit is:
- Accurate: It showed 94.7% sensitivity, 98.3% specificity, and 97.9% overall agreement in distinguishing macrometastases.
- Brief: The examination time is about 20 minutes for diagnosis.
- Cost-effective: It costs less than $30 for the kit and $3,000 for the automatic reader.
- Dual detection: It is possible to use the kit together with pathological diagnosis.
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