The clinical impact of 21-gene recurrence score on treatment decisions for patients with hormone receptor-positive early breast cancer in Korea.
OBJECTIVE
The 21-gene (Oncotype DX) recurrence score (RS) assay is useful in predicting the benefits of adjuvant chemotherapy for early breast cancer patients and is widely used in Western countries. However, to date, it has not gained much popularity in East Asia. We analyzed the results from five institutions' experience from using the 21-gene assay and examined the impact of assay results on decision making of chemotherapy in Korean breast cancer patients and the associations between RS and clinicopathologic characteristics.


METHODS
The 21-gene assay was performed on 212 patients with estrogen receptor-positive early breast cancer in five institutions. Each center made systemic treatment decisions both before and after the knowledge of assay results.


RESULTS
Among the 212 patients, 132 (62.3%) had a low RS of < 18, 60 (28.3%) had an intermediate RS of 18-30, and 20 (9.4%) had a high RS of ≥ 31. Histologic grade, presence of micrometastases, Ki-67, and presence of lymphatic invasion were statistically associated with the RS results. Treatment decisions were changed in 115 of 212 patients (54.2%) in 109 of 212 (51.4%) from chemotherapy plus hormone therapy to hormone therapy, and in six of 212 (2.8%) from hormone therapy to chemotherapy plus hormone therapy.


CONCLUSIONS
The 21-gene breast cancer assay proved to have a significant impact on treatment decision- making. The test reduces chemotherapy use in more than 50% of Korean estrogen receptor-positive, early breast cancer patients.
Center for Breast Cancer, National Cancer Center, Goyang, Korea.
Moo Hyun
MH
Lee
Department of Surgery, Seoul National University College of Medicine, Seoul, Korea.
Wonshik
W
Han
Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Jeong Eon
JE
Lee
Department of Surgery, Ajou University School of Medicine, Suwon, Korea.
Ku Sang
KS
Kim
Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Heeseung
H
Park
Department of Surgery, Seoul National University College of Medicine, Seoul, Korea.
Jongjin
J
Kim
Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Soo Youn
SY
Bae
Department of Surgery, Ajou University School of Medicine, Suwon, Korea.
Hyun Joo
HJ
Shin
Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Jong Won
JW
Lee
Center for Breast Cancer, National Cancer Center, Goyang, Korea.
Eun Sook
ES
Lee
Adjuvant chemotherapy; Breast neoplasms; Oncotype DX