Background: Management of occult primary breast cancer (OPBC), including the role of magnetic resonance imaging (MRI), is controversial. We conducted a pooled analysis of OPBC patients and a meta-analysis of MRI accuracy in OPBC in order to elucidate current practices.
Methods: A literature search yielded 201 studies. Patient-level data for clinically/mammographically OPBC from studies published after 1993 and from our institution were pooled; logistic regression examined associations between patient/study data and outcomes, including treatments and recurrence. We report adjusted odds ratios (OR) and 95 % confidence intervals (95 % CI) significant at 2-tailed p < 0.05. Meta-analysis included data for patients who received MRIs for workup of clinically/mammographically OPBC. We report pooled sensitivity and specificity with 95 % CIs.
Results: The pooled analysis included 92 patients (15 studies [n = 85] plus our institution [n = 7]). Patients from Asia were more likely to receive breast surgery (OR = 5.98, 95 % CI = 2.02-17.65) but not chemotherapy (OR = 0.32, 95 % CI = 0.13-0.82); patients from the United States were more likely to receive chemotherapy (OR = 13.08, 95 % CI = 2.64-64.78). Patients from studies published after 2003 were more likely to receive radiotherapy (OR = 3.86, 95 % CI = 1.41-10.55). Chemotherapy recipients were more likely to have distant recurrence (OR = 9.77, 95 % CI = 1.10-87.21). More patients with positive MRIs received chemotherapy than patients with negative MRIs (10 of 12 [83.3 %] vs 5 of 13 [38.5 %]; p = 0.0414). In the MRI-accuracy meta-analysis (10 studies, n = 262), pooled sensitivity and specificity were 96 % (95 % CI = 91-98 %) and 63 % (95 % CI = 42-81 %), respectively.
Conclusions: OPBC management varied geographically and over time. We recommend establishing an international OPBC patient registry to facilitate longitudinal study and develop global treatment standards.