Prognostic factors in non-metastatic HER2 ‘low’ and HER2 ‘negative’ breast cancer: single institute experience

Comparison of prognosis and survival in human epidermal growth factor receptor 2 (HER2)-low and HER2-negative patients with early stage or locally advanced, hormone receptor-positive breast cancer.

In a retrospective single center study, the patients with early stage or locally advanced stage, hormone receptor (HR)-positive [estrogen receptor (ER) ≥ 1% and/or progesterone receptor (PR) ≥ 1%] and HER2 negative or HER2 low invasive breast cancer diagnosis were included. A total of 444 patients were included in the study. Patients were divided into two groups: HER2 negative and HER2 low. There were 235 (53%) patients in the HER2 negative group and 209 (47%) patients in the HER2 low group.

The HER2 low group had significantly longer 5‑year disease-free survival (DFS) than the HER2 negative group. The patients with lower Ki67 (< 20%) also had a longer 5‑year DFS.

Nonmetastatic HR+/HER2 low breast cancer patients had better DFS than HR+/HER2 negative ones. The Ki67 level and HER2 low status were independent prognostic factors. Randomized clinical trials are needed in early stage HER2 low breast cancer patients.