Prognostic factors in Luminal B-like HER2-negative breast cancer tumors.

Background: Molecular and genomic platforms can classify breast cancer intrinsic subtypeswith precision, however these are not widespread and immunohistochemical (IHC) classification is still used globally. This study aimed to evaluate the main clinical and pathologic prognostic factors for Luminal B-like HER2-negative breast cancer in our clinical setting.

Methods: A retrospective review of early Luminal B-like HER2-negative breast cancer patients diagnosed in 2017 in our center was conducted. The main prognostic factors for relapse were evaluated, including patient's characteristics such as age, menopausal status, comorbidity index, personal and family history of breast cancer and obesity; tumor features such as size, histology and grade, oestrogen and progesterone receptor (PgR) status, HER2 status, Ki67 index and nodal involvement; and the given treatment. Cancer relapse during five years of follow-upwas considered the main outcome.

Results: Fifty-six patients with early Luminal B-like HER2-negative breast cancer were included. Seven patients relapsed within five years of follow-up. Lymph node involvement at diagnosis and postoperatively were significantly associated with relapse (24,5% vs 71,43%p = 0.022; 38,8% vs 83,3%p = 0.004, respectively),although the number of pathologic positive lymph nodes was not associated with relapse occurrence (mean 1.5 in no-relapse group vs 0.8 in relapse group; p = 0.308).Other possible risk factors such as young age, premenopausal status, self-history of breast cancer, tumor size, histologic grade, PgR, or Ki 67 were not significantly associated with relapse. Additionally, the distribution of the number of positive nodes among relapse and no relapse groups(2,1 vs 1,8; p = 0.082) was not significant.

Conclusions: Lymph node involvement was the only prognostic factor in Luminal B-like HER2-negative breast cancer identified in this study, independently of the number of affected nodes.