Low ER+ breast cancer: Is this a distinct group?
OBJECTIVE
Estrogen receptor (ER) level can be semiquantified by immunohistochemistry (IHC) using the H-score. The score, given as the sum of the percent staining multiplied by the intensity level, ranges from 0 to 300.


METHODS
Forty-nine ER+/HER2- invasive tumors with low ER expression (H-scores of 1-100, representing approximately 5% of all tumors) were studied for various morphologic parameters, progesterone receptor (PR), and Ki-67 IHC.


RESULTS
Eighteen of 49 patients received neoadjuvant chemotherapy. The morphologic analysis showed that these tumors are often grade 3 and frequently demonstrate a sheet-like growth pattern, an intratumoral lymphocytic inflammatory infiltrate, and necrosis. Eighty percent of tumors showed a Ki-67 proliferation index of more than 50%, and 94% were PR-. Of the 18 patients who received neoadjuvant chemotherapy, six (33%) achieved pathologic complete response.


CONCLUSIONS
The low ER+/HER2- cases have morphologic features and a response to the chemotherapy rate that are more similar to triple-negative tumors than the usual type of ER+ tumors.
Magee-Womens Hospital of University of Pittsburgh Medical Center, 300 Halket St, Pittsburgh, PA 15213; rbhargava@mail.magee.edu.
Nika C
NC
Gloyeske
David J
DJ
Dabbs
Rohit
R
Bhargava
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000378:metabolism; D001943:Breast Neoplasms / Q000737:chemistry* / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000032:analysis* / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism
D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human
Low ER+/HER2-; Morphology; Response to neoadjuvant chemotherapy