[312] Histopathologic Characteristics and Molecular Classification of Breast Cancer in Young Lebanese Women

Cleo Youssef Massad, Faysal Fedda, Fouad Boulos. American University of Beirut Medical Center, Beirut, Lebanon; University of Arkansas for Medical Sciences, Little Rock, AR

Background: Breast cancer in young women (<40 years) is known to have more aggressive biology, higher grade at presentation and more frequent ER receptor negativity than in older patients. Most available data is from western populations where about 7% of patients present at a young age. Studies have shown that in Lebanon and the Mideast, almost 50% of patients present before the age of 50, and that up to 22% present before age 40. It is not clear whether this difference in epidemiology is associated with a difference in the histopathologic and molecular features of breast cancer in our younger population. Our aim is to study the overall characteristics of breast cancer in young women from Lebanon in comparison to those of the same age group in the western population.
Design: 192 cases of breast cancer diagnosed in patients younger than 40 years between 1996 and 2010 with full available clinicopathologic information were reviewed. Variables including cancer type, tumor grade, estrogen and progesterone receptor status, and HER2/neu overexpression were analyzed. HER2/neu FISH testing results were available for equivocal cases diagnosed after 2009. The tumors were divided based on their receptor status into the molecular categories luminal A and B, Her2 amplified and triple negative/basal-like.
Results: Tumor types were as follows: Ductal (183/192, 95.3%), Lobular (5/192, 2.6%), Mucinous (4, 2.1%). Grades of tumors were distributed as follows: Grade 1 (18/192, 9.4%), grade 2 (64/192, 33.3%), and grade 3 (110/192, 57.3%). The molecular subtypes of 165/192 cases were determined, and were as follows: Luminal A (ER+, Her2-, low Ki-67): n= 61/165, 37%; Luminal B (ER+, Her2 +/-, high Ki-67): n= 43/165, 25.5%; Triple negative/Basal-like (ER-, Her2-): n= 39/165, 23.6%; Her2 amplified (ER-, Her2+): n= 22/165, 13.3%. In 14.1% (n= 27/192) of cases, the molecular type could not be determined because of equivocal Her2 results. 23/27 of these cases were of a luminal subtype (ER+).
Conclusions: Despite a greater proportion of breast cancer in young women from Lebanon, the histopathologic characteristics and distribution of luminal subtypes is comparable to the western world, but with a significantly lower rate of triple negative/basal-like neoplasms (23.6% vs. 42%). Our results suggest that, although more frequent, breast cancers in young Lebanese women may have a different biology and a less aggressive phenotype than their western counterparts.
Category: Breast

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 26, Wednesday Afternoon


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