ABSTRACT
Background: At the 13th St Gallen International Breast Cancer Conference in
2013, a new definition of luminal A-like and luminal B-like breast cancer was proposed,
involving the expression of estrogen receptor (ER), progesterone receptor (PgR),
and Ki-67. We examined the rate of concordance between the risk groups using the
Oncotype DX recurrence score (RS) and the previous and newly proposed luminal subtypes
with the standardized Ki-67 assessment. Method: The relationship between a previously
and newly proposed, immunohistochemically defined luminal A and B subtype with the
Oncotype DX RS of 41 cases of T1-2 N0-1 M0 (ER positive, HER2 negative) breast cancer
was assessed. We first classified the patients into the previously defined luminal
A and B subtypes, according to the level of Ki-67 as either “low” (<14%) or “high”
(≥14%), as assessed by local pathologists. Next, to consider the necessity for standardizing
Ki-67 measurement methods, we re-examined Ki-67 with a central review. By introducing
PgR positivity (≥20%), we classified these patients to newly proposed luminal subtypes
and compared them with the risk groups stratified by Oncotype DX RS. Results: In
the previously proposed luminal subtypes, the concordance rate between luminal A
and the low RS category was 76.5% according to local pathologists and 90.1% by central
review, whereas the rate between luminal B and the intermediate to high RS category
was 46.7% and 45.8%, respectively. In newly proposed luminal subtypes, the concordance
rate between luminal A and low RS category was 100% and between the luminal B and
intermediate to high RS category was 53.6%. Conclusions: Although this study was
based on a retrospective chart review of a small sample size, the newly proposed
luminal subtypes including addition of PgR positivity with the standardized Ki-67
assessment appeared to improve the concordance rate especially between luminal A
and low RS category.
Share and Cite:
Mizuno, Y. , Fuchikami, H. , Takeda, N. , Yamada, J. , Inoue, Y. , Seto, H. and Sato, K. (2016) Comparing Oncotype DX Recurrence Score Categories with Immunohistochemically Defined Luminal Subtypes.
Journal of Cancer Therapy,
7, 223-231. doi:
10.4236/jct.2016.73023.