Study of Molecular Subtypes and Clinic-PathoLogical Features of Breast Cancer in Iraq

Breast cancer is the most common cancer in women worldwide constituting 25.1% of all new cancer cases. In 2012, worldwide breast cancer deaths were approximately 521, 907 as reported by GLOBOCAN data base. The histopathological classification essentially plays a role in identifying the various histologic variants of breast carcino-ma; namely, tubular, medullary, mucinous/colloid carcinomas, and others. A new therapeutically relevant molecular clas-sification has been developed, based on gene expression profiling using complementary DNA microarrays. This observational retrospective study was carried out in Al-Amal national hospital for cancer treatment / Baghdad during the period from January 2012 to December 2016. A total of 250 women were selected with excluding male patients, recur-rent cases. The following archival information were obtained from each patient using KHUH's laboratory information sys-tem: age at diagnosis, tumor size, histopathological subtype, presence or absence of carcinoma in situ, lymph node status and immunohistochemical profile of the hormonal receptors ER and PR, and immunohistochemical profile of HER2 in the invasive malignant cells. The tumor size measurement was obtained on ultrasound reports of the breast prior to bi-opsy. The number of lymph nodes identified and the number of lymph nodes positive for metastasis were determined. The immunohistochemical antibodies used for estrogen, progesterone, and HER2 are anti-estrogen receptor antibody (SP1), anti-progesterone receptor antibody (1E2), and anti-HER-2 (4B5) rabbit monoclonal primary antibody. The diagnosis, SBR grading, and hormonal receptor and HER2 status assessment were carried out and verified independently by at least 2 qualified histopathologists. Results of this study showed that breast cancer classification by immunohistochemistry revealed that in our community luminal A tumors were the most common subtype, followed by the rest tumors. Breast cancer subtypes exhibited particu-lar characteristics. Luminal A tumors were associated with an increased frequency of ductal carcinomas. The HER2-positive and triple negative tumors were associated with an increased frequency of a large tumor size and poorly differen-tiated carcinomas and are thereby more aggressive. In addition, triple negative tumors least frequently showed a compo-nent of carcinoma in situ. It can be concluded from our study that there is no correlation between lymph node status and molecular subtypes.