Abstract P6-06-54: Analysis of treatment and survival of pathologic occult breast cancer with axillary lymph node metastasis: Nationwide retrospective study

Objective Occult breast cancer (OBC) is a rare presentation which accounts for 0.3-1.0% of all breast cancers. In spite of limited information, there is no consensus regarding the prognostic factors and treatment of OBC. This retrospective study intends to evaluate the overall survival and prognostic factors of occult breast cancer (OBC) in Korea. Method This study included 142 pathologic occult breast cancer patients from January 1990 to December 2009, identified from Korean Breast Cancer Society cancer registry. All patients had pathologically positive axillary lymph node (N1-N3) along with pathologically & radiologically negative in-breast lesion (T0/Tx) based on retrospective review of database. Among 142 patients, 32 patients had only axillary lymph node dissection (ALND), 56 patients had breast conserving operation (BCO) with ALND and 54 patients had mastectomy with ALND. 96 patients (96%) had N1 disease, 23 patients (16.2%) had N2 disease and 23 patients (16.2%) had N3 disease. Results There was no significant statistical difference in overall survival among different operation method, which is ALND only, BCO with ALND, mastectomy with ALND (p = 0.061), considering that 12 patients (37.5%) among 32 patients who only had ALND had N3 disease comparing that only 7 (12.5%) out of 56 patients and 4 (7.4%) out of 54 patients had N3 disease in BCO with ALND and mastectomy with ALND group separately. Univariate analysis revealed that only nodal status was significant prognostic factor (p = 0.0004), and other factors including radiotherapy (p = 0.696), chemotherapy (p = 0.302), estrogen receptor positivity (p = 0.144), progesterone receptor positivity (p = 0.254), total number of removed lymph node (p = 0.586) didn9t show statistical difference in overall survival. Conclusions This study suggests that OBC patients who only had ALND showed similar outcomes when comparing with patients who had BCO with ALND or mastectomy with ALND. Also only nodal status might be independent predictors for poor outcomes of occult breast cancer. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-06-54.