title: MUC1 is expressed at high frequency in early-stage basal-like triple-negative breast cancer.
abstract: Triple-negative breast cancer comprises 10% to 15% of newly diagnosed breast cancer and lacks expression of the estrogen, progesterone, and human epidermal growth factor receptor 2/neu receptors. Many such tumors are basal like, a molecular intrinsic subtype of breast cancer associated with poor clinical outcomes. Patients with early-stage basal-like triple-negative breast cancer are at a high risk for relapse and may, therefore, benefit from novel therapies, including immunotherapy. MUC1 is a tumor antigen expressed on adenocarcinomas and represents an ideal target for MUC1-based vaccination. We evaluated 52 cases of early-stage basal-like triple-negative breast cancer for MUC1 expression by immunohistochemistry. The intensity of staining was graded according to the intensity (negative [0], positive [1], or strongly positive [2]) and percentage (0%-100%) of tumor cells staining for MUC1. An overall score of 0 to 2.0 was calculated for each case by multiplying the intensity of staining by the percentage of tumor cells staining positively. Four staining patterns for MUC1 were identified: apical, cytoplasmic, membranous, and combination. Of the 52 cases of basal-like triple-negative breast cancers, 49 (94%) were positive for MUC1 expression. The mean score was 0.90 (range, 0-1.9). Cases were evenly distributed over this range, where most (67%) exhibited moderate to strong MUC1 expression (score, 0.5-1.90), 27% demonstrated weak MUC1 expression, and 6% lacked MUC1 expression. There was a significant difference in MUC1 score and percent MUC1+ cells in favor of the combination pattern. This study indicates that a large proportion of early-stage basal-like triple-negative breast cancer expresses MUC1 and provides a rationale for MUC1-based immunotherapy in this high-risk patient cohort.
authors.affiliation: Department of Pathology, University Hospitals Seidman Cancer Center, Cleveland, OH 44106.
authors.forename: Alan
authors.initials: A
authors.lastname: Siroy
authors.forename: Fadi W
authors.initials: FW
authors.lastname: Abdul-Karim
authors.forename: John
authors.initials: J
authors.lastname: Miedler
authors.forename: Nancy
authors.initials: N
authors.lastname: Fong
authors.forename: Pingfu
authors.initials: P
authors.lastname: Fu
authors.forename: Hannah
authors.initials: H
authors.lastname: Gilmore
authors.forename: Joseph
authors.initials: J
authors.lastname: Baar
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D008875:Middle Aged; D018396:Mucin-1 / Q000378:metabolism*; D009367:Neoplasm Staging; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D018396:Mucin-1; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C060192:MUC1 protein, human
keywords: Basal-like; Mucin; Triple-negative breast cancer