PURPOSE

We evaluated the concordance between core needle biopsy (CNB) and surgical specimens on examining intrinsic biological subtypes and receptor status, and determined the accuracy of CNB as a basic diagnostic method.

METHODS

We analyzed breast cancer patients with paired CNB and surgical specimen samples during 2014. We used monoclonal antibodies for nuclear staining, and estrogen receptor (ER) and progesterone receptor (PR) status evaluation. A positive test was defined as staining greater than or equal to 1% of tumor cells. Human epidermal growth factor receptor 2 (HER2) was graded by immunohistochemistry and scored as 0 to 3+ according to the recommendations of the American Society of Clinical Oncology/College of American Pathologists. Ki-67 immunostaining was performed using the monoclonal antibody Ki-67, and the results were divided at 10% intervals. The cutoff value for high Ki-67 was defined as 20%. Concordance analysis of ER, PR, HER2, Ki-67, and five intrinsic biological subtypes was performed on CNB and surgical specimens. Statistical analysis for concordance was calculated using κ-tests.

RESULTS

We found very good agreement for ER and PR with a concordance of 96.7% for ER (κ=0.903), and 94.3% for PR (κ=0.870). HER2 and Ki-67 showed concordance rates of 84.8% (κ=0.684) and 83.5% (κ=0.647), respectively, which were interpreted as good agreement. Five subgroups analysis showed 85.8% agreement and κ-value of 0.786, also indicating good agreement.

CONCLUSION

CNB showed high diagnostic accuracy compared with surgical specimens, and good agreement for ER, PR, HER2, and Ki-67. Our findings reaffirmed the recommendation of CNB as an initial procedure for breast cancer diagnosis, and the assessment of receptor status and intrinsic biological subtypes to determine further treatment plans.