Provisional Guideline Recommendation for EGFR Gene Mutation Testing in Liquid Samples of Lung Cancer Patients: A Proposal by the Korean Cardiopulmonary Pathology Study Group

Liquid biopsy for detection of mutation from circulating tumor DNA is a new technology which is attractive in that it is non-invasive. Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) is an effective first line drug for advanced non-small cell lung cancer patients who harbor activating EGFR mutation. During the course of treatment, resistance against TKI arises which can be contributed to EGFR T790M mutation in about 50–60% of patients. Third generation TKI may overcome the resistance. In patients who cannot undergo tissue biopsy due to variable reasons, liquid biopsy is an excellent alternative for the detection of EGFR T790M mutation. However, this relatively novel method requires standardization and vigorous quality insurance. Thus, a standard set of guideline recommendations for liquid biopsy for EGFR mutation testing suitable for the Korean medical community is necessary. In this article, we propose a set of provisional guideline recommendations that was discussed and approved by the Cardiopulmonary Pathology Study Group of the Korean Society of Pathologists.

Analysis of the Clinicopathological Features in the Micrometastasis and the Macrometastasis in Sentinel Lymph Node of Primary Breast Cancer

PURPOSE: The aim of this study was to compare the micrometastasis group with the macrometastasis group, and to analyze clinical and pathological variables to determine what factors might predict non-sentinel lymph node (NSLN) involvement in the women with sentinel nodes that contained only micrometastasis. METHODS: Between June 2003 and September 2005, 650 patients with primary breast cancer and who underwent a SLN procedure were retrospectively reviewed. Of those 650 patients, 138 patients with metastasis in the SLNs were analyzed. RESULTS: The median number of harvested sentinel lymph nodes (SLNs) was 2.5 (range: 1~7) and the median number of tumor positive LNs was 2.1 (range: 1~22). Of the 138 patients with a positive SLN, macrometastasis was identified in 105 patients and micrometastasis was noted in 33 patients. The SLN micrometastases were smaller than 0.2 mm in 18 patients and it was between 0.2 to 2.0 mm in 15 patients. Completion axillary dissection was performed in 17 (51.5%) patients with SLN micrometastasis and in 105 (100%) patients with SLN macrometastasis. NSLN involvement was found in 43/105 (41.0%) patients with SLN macrometastasis, while it was not found in the patients with SLN micrometastasis. Univariate analysis showed that T stage, multiplicity, lymphovascular invasion and histologic type were significantly associated with the difference between micrometastasis and macrometastasis in the SLNs. Multivariate analysis identified T stage as a significant factor. CONCLUSION: This study suggests that NSLN metastasis is associated with size of metastasis found in the SLN and completion axillary dissection may not be necessary in patients who have micrometastatic disease in the SLN.