Molecular Phenotype of Pregnancy Associated Breast Cancers (PABC) in a Large Cohort of Young Women
S Demski, S Gelber, J Marotti, K Cole, S Kereakoglow, K Ruddy, E Brachtel, L Schapira, S Come, V Borges, P Schedin, E Warner, E Winer, A Partridge, L Collins. Beth Israel Deaconess Medical Center, Boston; Dana Farber Cancer Institute, Boston; Dartmouth-Hitchcock Medical Center, Lebanon; Massachusetts General Hospital, Boston; University of Colorado Cancer Center, Denver; Sunnybrook Odette Cancer Centre, Toronto, Canada
Background: The increase in breast cancer risk during pregnancy and post-partum is well known; however the molecular phenotype of PABCs has not been well studied. A genomic signature specific to the pregnant breast, which remains present postmenopausally, has been identified. Given this, we investigated whether the time interval since pregnancy affects the phenotype of breast cancers in parous vs. nulliparous young women.
Design: We examined molecular phenotype, determined by histologic grade on central review and biomarker status by report, in relation to time since pregnancy in a prospective study (n=359) of young women (≤40yrs) with breast cancer. Parity was ascertained from study questionnaires. Using tumor grade and biomarker expression, cancers were categorized as luminal A or B, HER2-type and triple negative (TN).
Results: Overall, 67% of cancers were ER+ and 29% were HER2+. There were no differences in the distribution of molecular phenotype according to time interval since pregnancy.
|Molecular Phenotype||Nulliparous N=132 (37%)||<= 2 years N=54 (15%)||>2-5 years N=74 (21%)||>5 years N=99 (28%)||Total patients N=359|
|Luminal A (ER/PR+, HER2-, grade 1 or 2)||54 (41)||17 (31)||18 (24)||34 (34)||123 (34)|
|Luminal B (ER/PR+, HER2+ or ER/PR+, HER2-, grade 3)||45 (34)||19 (35)||26 (35)||34 (34)||124 (35)|
|HER2 type (ER-, PR-, HER2+)||9 (7)||6 (11)||13 (18)||9 (9)||37 (10)|
|Triple negative (ER, PR, HER2-)||24 (18)||12 (22)||17 (23)||22 (22)||75 (21)|