Prognosis and therapeutic choices for occult breast cancer in female patients: a systematic review and meta-analysis

Occult breast cancer (OBC) is a rare subtype characterized by axillary lymph node (LN) metastasis without an identifiable primary breast lesion. Owing to its rarity, optimal management remains controversial. We performed a systematic review and meta-analysis to comprehensively evaluate the clinicopathological characteristics, prognosis, and treatment outcomes of female patients with OBC. A systematic review and meta-analysis were conducted using PubMed/MEDLINE, Embase, and the Cochrane Library to identify eligible studies published after 2000. Female patients with OBC (T0N+M0) were included. Primary outcomes were overall survival (OS) and disease-free survival (DFS), analyzed according to LN stage and treatment strategies. Thirty retrospective studies involving 6,001 patients were included. The pooled treatment proportions were 30% for mastectomy plus axillary lymph node dissection (ALND), 42% for ALND alone, and 68% for radiotherapy (RT). The pooled proportions of N1, N2, and N3 disease were 62%, 20%, and 12%, respectively. The pooled 5-year and 8-year OS rates were 90% and 64%. Compared with N1 disease, patients with N2-3 disease had significantly worse OS (HR 6.10, 95% CI 2.19-16.95). Mastectomy was not significantly associated with OS or DFS. RT was associated with improved OS (HR 0.60), whereas no significant association with DFS was observed. Female patients with OBC appear to have relatively favorable survival outcomes, while axillary nodal stage remains an important prognostic factor. Mastectomy was not associated with a clear survival advantage. RT appeared to be associated with improved OS; however, this finding should be interpreted cautiously because the available evidence was derived primarily from retrospective observational studies, and its effect on DFS remains uncertain. Further prospective studies are warranted to optimize treatment strategies for OBC. CRD42024535815