Mai Yamada1, Makoto Kubo2, Hidetaka Yamamoto3, Nami Yamashita4, Masaya Kai1, Karen Zaguirre5, Kazuhisa Kaneshiro1, Akiko Shimazaki1, Saori Hayashi1, Hitomi Kawaji1, Masaki Mori4, Yoshinao Oda3, Masafumi Nakamura1. 1. Department of Surgery and Oncology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. 2. Department of Surgery and Oncology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan mkubo@surg1.med.kyushu-u.ac.jp. 3. Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. 4. Department of Surgery and Science, Kyushu University, Fukuoka, Japan. 5. Institute of Surgery, St. Luke's Medical Center, Quezon, Philippines.
Abstract
BACKGROUND/AIM: With advances in anti-HER2 treatment and improved prognoses of HER2-positive breast cancer, the American Society of Clinical Oncology and the American Society of Pathologists (ASCO/CAP) have revised the HER2 diagnostic guidelines several times. We examined how to respond clinically to the revisions of the interpretation of the immunohistochemistry (IHC) method. PATIENTS AND METHODS: We re-evaluated 254 patients diagnosed as HER2 IHC equivocal, who underwent fluorescence in situ hybridization (FISH) before and after the IHC diagnostic criteria update in 2013. RESULTS: Twenty of 131 (15.3%) IHC equivocal cases by the ASCO/CAP 2007 guideline were IHC score 3+ and one of 20 (0.76%) was negative for FISH. Five of 123 (4.1%) IHC equivocal cases by the ASCO/CAP 2013 guideline were negative for IHC as per the 2007 guideline and four were positive for FISH. CONCLUSION: After revision of the ASCO/CAP 2013 guideline, 3.3% of HER2-negative cases before the revision should have received anti-HER2 treatment.
BACKGROUND/AIM: With advances in anti-HER2 treatment and improved prognoses of HER2-positive breast cancer, the American Society of Clinical Oncology and the American Society of Pathologists (ASCO/CAP) have revised the HER2 diagnostic guidelines several times. We examined how to respond clinically to the revisions of the interpretation of the immunohistochemistry (IHC) method. PATIENTS AND METHODS: We re-evaluated 254 patients diagnosed as HER2 IHC equivocal, who underwent fluorescence in situ hybridization (FISH) before and after the IHC diagnostic criteria update in 2013. RESULTS: Twenty of 131 (15.3%) IHC equivocal cases by the ASCO/CAP 2007 guideline were IHC score 3+ and one of 20 (0.76%) was negative for FISH. Five of 123 (4.1%) IHC equivocal cases by the ASCO/CAP 2013 guideline were negative for IHC as per the 2007 guideline and four were positive for FISH. CONCLUSION: After revision of the ASCO/CAP 2013 guideline, 3.3% of HER2-negative cases before the revision should have received anti-HER2 treatment.