Abstract: Objective:Occult breast cancer (OBC) accounts for 0.3%-1.0% of all breast cancers. Because of the rarity of this dis-ease, its treatment and prognosis remain unclear. Our study evaluated the treatment outcomes and prognostic factors associated with OBC.Methods:A total of 82patients diagnosed with OBC based on available criteria were treated at the Cancer Hospital of Chinese Academy of Medical Sciences, Beijing, China, between January 1968and June 2014. Except for 16patients who were treated by needle biopsy or excisional biopsy only and were subsequently excluded, all of the cases reported were included in the study. Of the remaining 66patients, one was male. Patient data, tumor characteristics, and treatment and outcome variables were evaluated. Overall survival (OS) and disease- free survival (DFS) were analyzed. A unicentric retrospective review of 66patients with OBC was performed. Re-sults: The median follow-up was75.5 months (7.0- 328.0). No significant differences in OS and DFS were observed between patients who underwent mastectomy plus axillary lymph node dissection (Mast+ALND) and those who underwent breast conservation surgery (P>0.05). Univariate analysis revealed that nodal status is a significant prognosis factor of DFS (P=0.031). Conclusion:No significant difference in treatment outcomes between mastectomy+ALND and breast conservation surgery was observed. Nodal status may be an independent predictor of poor outcomes in OBC patients.