Prognostic factor analysis and clinical significance of HER‑2‑positive breast cancers with negative lymph nodes and a tumor diameter ≤1 cm

The 2021 National Comprehensive Cancer Network guidelines recommend that adjuvant chemotherapy combined with trastuzumab be considered for human epidermal growth factor receptor 2 (HER-2)-positive breast cancer patients with small tumors (tumor diameter ≤1 cm) and negative lymph nodes. Additionally, the prognostic factors and clinical significance of HER-2-positive breast cancer with negative lymph nodes and a tumor diameter ≤1 cm remain unclear. In the present study, the clinical data and prognostic factors of 87 patients with HER-2-positive breast cancer with negative lymph nodes and a tumor diameter ≤1 cm admitted to Guangdong Women and Children Hospital from January 2013 to December 2019 were retrospectively analyzed. The median follow-up time was 70 months, the disease-free survival (DFS) of all patients was 94.3% and the overall survival (OS) was 100%. Univariate analysis of prognosis demonstrated that patients aged ≤40 years had significantly lower DFS than those aged >40 (80.8 vs. 100.0%, P<0.001). DFS was significantly improved in patients who were hormone-receptor-positive and patients who received endocrine therapy compared with patients who were estrogen receptor negative and patients who did not receive endocrine therapy (100.0 vs. 89.6%, P=0.039; 100.0 vs. 90.0%, P=0.049). Prognostic univariate analysis demonstrated that patient age, hormone receptor status and use of endocrine therapy were significantly related to the DFS (P<0.05), while none of these were independent factors related to the DFS in the prognostic multivariate analysis (P=0.240, P=0.976 and P=0.925). The proportion of patients with a tumor diameter 0.5-1 cm receiving adjuvant anti-HER-2 treatment was significantly greater compared with patients with tumors with a diameter ≤0.5 cm (46.4 vs. 18.6%, P<0.05). There was no significance difference in the DFS of patients treated with adjuvant chemotherapy with or without anti-HER-2 therapy with tumor diameters ≤0.5 cm (P>0.05), but there was a significant difference in the DFS of patients with a tumor diameter 0.5-1 cm (P<0.05). These results suggested that adjuvant chemotherapy, with or without anti-HER-2 therapy, may affect the prognosis of HER-2-positive breast cancer patients with negative lymph nodes and a tumor diameter of 0.5-1 cm. Therefore, it could be recommended that such patients receive adjuvant chemotherapy and anti-HER-2 therapy in the future.