Treatment outcomes and unfavorable prognostic factors in patients with occult breast cancer.

Abstract Aims The purpose of this study was to evaluate the treatment outcomes and prognostic factors in patients with occult breast cancer (OBC). Methods We retrospectively analyzed 95 patients with OBC who were treated at our facility between January 1998 and June 2010. Of the 95 patients, 64 underwent mastectomy plus axillary lymph node dissection (ALND) with or without post-mastectomy radiation (Mast + ALND group), 13 underwent ALND followed by ipsilateral breast radiotherapy (BR + ALND group) and the remaining 18 were treated with ALND (ALND group). Results Patients who underwent Mast + ALND or BR + ALND had significantly improved rates of locoregional recurrence-free survival (LRFS) and recurrence/metastasis-free survival (RFS) than patients who only underwent ALND ( p p  = 0.718), RFS ( p  = 0.935) and breast cancer-specific survival (BCSS) ( p  = 0.991) rates between the patients who underwent Mast + ALND compared with those who received BR + ALND. Multivariate analysis revealed that patients with four or more involved lymph nodes had significantly worse outcomes ( p  = 0.042, HR = 4.63, 95% CI = 1.66–32.47 for BCSS and p  = 0.038, HR = 3.62, 95% CI = 1.08–20.77 for RFS). Conclusions Patients with OBC who received ALND and subsequent breast radiotherapy had similar outcomes to patients who underwent mastectomy. The presence of four or more involved lymph nodes may independently predict poor outcomes of OBC.