A retrospective study was undertaken to determine and compare the prognostic significance of LEA-135 protein expression by immunohistochemistry with other prognostic pathological parameters, with respect to recurrence and overall survival. This study was conducted in freshly-frozen tissue sections from a cohort of 367 patients having primary invasive breast cancer, with axillary lymph node metastasis. The association of LEA-135 expression was compared with estrogen and progesterone receptor status, segmentectomy or radical mastectomy and hormonal therapy or chemotherapy in terms of recurrence or disease-free survival. Pathologic parameters including tumor size, histological tumor type and histological grade, as well as age of patients at the time of initial diagnosis, and the treatments, together with a median follow-up of 8.8 years were contemplated for the study. Among these parameters, tumor size and histological grade were individually and significantly associated with an increased probability of recurrence (log rank p<0.001 in both cases) and short survival (log ranks p<0.001 and p=0.002, respectively), whereas age was only significantly associated with an increased probability of recurrence (log rank p=0.002) by univariate analysis. By multivariate analysis, both tumor size and histological grade remained statistically significant for recurrence (log rank p<0.001 and p=0.013, respectively) and overall survival (log ranks p<0.001 and p=0.016, respectively). Among the prognostic biomarkers, both ER and PR expression were associated with a decreased rate of recurrence (log ranks p<0.001 and p=0.008, respectively) and overall survival (log ranks p<0.001 and p=0.002, respectively) by univariate analysis. By multivariate analysis, only the ER expression remained significantly associated with a decreased recurrence and increased overall survival (log ranks p=0.023 and p=0.002, respectively). Patients with high (>50% positive cells) or moderate (5-50% positive cells) number of LEA-135-positive cells had a lower probability (46%) of recurrence at 10 years after surgery compared to 76% in LEA-135-negative patients (log rank p<0.001) by univariate analysis. Moreover, the probability of overall survival was higher in patients with high or moderate expression of LEA-135 (46% and 47%, respectively) compared to LEA-135-negative patients (24%) by univariate analysis (log rank p=0.009). By multivariate analysis, the association remained statistically significant for recurrence (log rank p<0.001) and survival (log rank p=0.002). However, there was no significant association between LEA-135 and any of the pathological parameters, age, hormone receptor status, the mode of surgery or the form of therapy (chemo- and/or hormonal) received by this cohort of patients. The results show that an improved prognosis was directly associated with the density of LEA-135-positive cancer cells, while loss of LEA-135 expression was associated with an aggressive phenotype of cancer cells during breast cancer progression. Thus, LEA-135 expression can be implicated as a significant and independent biomarker to identify and distinguish high- from low-risk patients with lymph node-positive invasive breast cancer for an aggressive treatment. Moreover, according to the present results, LEA-135 expression appears to be associated with the tumor cells that have retained certain normal biological characteristics, leading to their lack of aggressiveness and hence a better prognosis.