Luminal A or B?

Racy,  In all the material I've read, ER and PR at 90 % would classify you as Luminal A for IDC.  I've been reading paying attention to IDC, not ILC though.  

There doesn't yet seem to be full consensus on what is what in the literature. Generally, luminal A and B are not determined by tumor size or nodal involvement but by ki-67 score, and luminal B in some articles has included Her2-positive cancers.

Here is one abstract (to muddy the waters, I'm afraid):

BACKGROUND:

The St Gallen International Expert Consensus 2011 has proposed a new classification system for breast cancer. The purpose of this study was to elucidate the relationship between the breast cancer subtypes determined by the new classification system and genomic characteristics.

METHODS:

Invasive breast cancers (n = 363) were immunohistochemically classified as follows: 111 (30.6%) as luminal A, 95 (26.2%) as luminal B (HER2 negative), 69 (19.0%) as luminal B (HER2 positive), 41 (11.3%) as HER2, and 47 (12.9%) as basal-like subtypes.

RESULTS:

The high expression of Ki-67 antigen was detected in 236 tumors; no cases of luminal A subtype showed high expression of the Ki-67 antigen, but more than 85% of tumors of the other subtypes showed high expression. In addition, DNA ploidy and chromosomal instability (CIN) were assessed using imaging cytometry and FISH, respectively. In this series, 336 (92.6%) tumors consisted of 129 diploid/CIN- and 207 aneuploid/CIN + tumors. Diploid/CIN- and aneuploid/CIN+ features were detected in 64.9% and 27.9% of luminal A, 41.1% and 49.5% of luminal B (HER2-), 11.6% and 81.2% of luminal B (HER2+), 4.9% and 90.2% of HER2, and 17.0% and 76.6% of basal-like subtypes, respectively. Unlike the luminal B (HER2+), HER2 and basal-like subtypes, the luminal A and luminal B (HER2-) subtypes were heterogeneous in terms of DNA ploidy and CIN.

CONCLUSIONS:

It is reasonable to propose that the luminal A and luminal B (HER2-) subtypes should be further divided into two subgroups, diploid/CIN- and aneuploid/CIN+, based on their underlying genomic status.

http://www.ncbi.nlm.nih.gov/pubmed/22830453

The difference that experts agree on is that luminal A and B can be distingushed by outcomes, with luminal A having a better prognosis than B. But this doesn't mean YOU, individually, have a bad prognosis. Studies look at group trends, not at individuals.

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Here is a bit more:

Abstract

The 12th St Gallen International Breast Cancer Conference (2011) Expert Panel adopted a new approach to the classification of patients for therapeutic purposes based on the recognition of intrinsic biological subtypes within the breast cancer spectrum. For practical purposes, these subtypes may be approximated using clinicopathological rather than gene expression array criteria. In general, systemic therapy recommendations follow the subtype classification. Thus, 'Luminal A' disease generally requires only endocrine therapy, which also forms part of the treatment of the 'Luminal B' subtype. Chemotherapy is considered indicated for most patients with 'Luminal B', 'Human Epidermal growth factor Receptor 2 (HER2) positive', and 'Triple negative (ductal)' disease, with the addition of trastuzumab in 'HER2 positive' disease. Progress was also noted in defining better tolerated local therapies in selected cases without loss of efficacy, such as accelerated radiation therapy and the omission of axillary dissection under defined circumstances. Broad treatment recommendations are presented, recognizing that detailed treatment decisions need to consider disease extent, host factors, patient preferences, and social and economic constraints.

http://www.ncbi.nlm.nih.gov/pubmed/21709140

Only the tip of the iceberg. The discussion continues....

Coming - I can't find the link now, but when this first came out I did a lot of research on it because my dx was also years ago.  From what I read at the time, there were differences in survival rates in Luminal A or B up till the 5 year mark, but then after that, there was no statistically significant difference in survival between the two subtypes.  Since I'm 5 years out, it appeared that the issue just didn't apply any more to me.  Last time I saw my onc, she confirmed that. 

It looks like from your sig you're just over 4 years out now.  In another year this will not be statistically significant for you, and my guess is that even after 4 the statistical differences is survival and recurrance are small.