IS MOLECULAR SUBTYPES OF BREAST CANCER RELATED WITH AXILLARY INVOLVEMENT? A RETROSPECTIVE STUDY OF 86 CASES

ENVER ILHAN¹, ORHAN UREYEN¹, OZCAN ALPDOGAN¹, ABDULLAH SENLIKCI¹, DEMET ALAY¹, UGUR GOKCELLI¹, ULVI MEHMET MERAL²

¹Department of General Surgery, Bozyaka Research and Training Hospital, Izmir, Turkey - ²General Surgery, Izmir Military Hospital, Turkey

Introduction: Gene expression analysis has identified several molecular subtypes of breast cancer. This classification of subty- pes is important for the treatment and prognosis of the disease. The relationship between molecular subtypes of breast cancer and axil- lary involvement remains controversial. The purpose of this study is to examine whether there is a relationship between molecular subtypes and axillary involvement in breast cancer, and whether such relationshipis useful in the decision of surgical interventions for the axilla.

Materials and methods: Medical records of 86 patients with breast cancer were examined retrospectively. Data were collected on thefollowing independent variables: age, gender, menopausal status, neoadjuvant treatment, tumor size, axillary involvement, TNM stage, histologic type and grade, estrogen receptor(ER), progesterone receptor (PR), HER-2 status, and the presence of p53 and Ki-67 gene expression. Patients in this cohort were grouped according to their molecular subtypes of the breast cancers as defined by the St. Gallen International Expert Consensus 2013. The relationship between molecular subtypes and nodal involvement was investigated and compared in terms of independent variables. In addition, Luminal A and Luminal B subtypes were compared with each other.

Results: There were 20 (23.2%), 47(54.6%), 8(9.3%), and 4(4.6%)patients in the Luminal A, Luminal B, HER-2 (+), and Triple Negative(TN) groups, respectively. p53 gene expression was different in the TN group when compared with that in the Luminal A and B groups(p<0.05). There were no significant differences in any other independent variables among the molecular subtype groups. Overall, 40 (46.4%) patients had nodal involvement. Age, molecular subtypes of cancer, histologic grade, and hormone receptor status had no discernible effect on nodal involvement. Tumor stage correlated with nodal involvement(p<0.05).

Conclusion: We were not able to find an association between nodal involvement and molecular subtypes of breast cancer in this study. Therefore, the prediction of axillary involvement based on the identification of molecular subtypes of breast cancer may not be possible, according to these results.