Occult Breast Cancer Presenting with Axillary Lymph Node Metastasis: A Clinicopathological Analysis and Survival Outcomes

AbstractAim: Occult breast cancer (OBC) is a rare clinical entity characterized by axillary lymph node metastasis without a detectable primary tumor in the breast. This study aimed to evaluate the clinicopathological features and the impact of different treatment modalities on survival in patients diagnosed with OBC.Methods: A total of 14 patients diagnosed with OBC between 2016 and 2024 were retrospectively analyzed. Diagnosis was confirmed clinically and through multimodal imaging, including ultrasonography, mammography, magnetic resonance imaging (MRI), and positron emission tomography/computed tomography (PET-CT). Demographic data, immunohistochemical profiles, surgical interventions, systemic therapies, and survival rates were evaluated.Results: The cohort was predominantly female (92.9%), with a mean age of 54.6 years. The most common presenting symptom was a palpable axillary mass (71.4%). Molecular subtypes were identified as Luminal A (50%), Luminal B (35.7%), and Triple-Negative (14.3%). The 5-year survival rate was 100% in patients who underwent either modified radical mastectomy (MRM) or breast-conserving surgery (BCS) combined with axillary lymph node dissection (ALND). In contrast, the survival rate was 50% for those who underwent ALND alone and 0% for those who received no surgical intervention (p=0.003). While radiotherapy was associated with a higher 5-year survival rate compared to no radiotherapy (90.9% vs. 50%), this difference was not statistically significant (p=0.083). No significant associations were found between survival and age, smoking status, neoadjuvant chemotherapy, or endocrine therapy (p>0.05).Conclusions: Multimodal treatment is essential for OBC. Breast-directed surgery combined with axillary dissection significantly improves survival compared to either axillary dissection alone or no surgical intervention.