Prognosis of lymph node-negative breast cancer: Association with clinicopathological factors and tumor associated gene expression

The aim of the present study was to investigate the association between the prognosis of lymph node-negative breast cancer patients and clinicopathological factors, as well as the association between tumor-associated gene expression and prognosis. Clinical data and survival information was collected for 341 patients with lymph node-negative breast cancer, admitted to the Cancer Hospital of the Chinese Academy of Medical Sciences (Beijing, China) from 1995 to 1999. Kaplan-Meier survival analysis and Log-rank tests were used to evaluate the association of clinical parameters and prognosis. In addition, the gene expression of HER2, TOP2A and CCND1 in patients with good [disease-free survival (DFS), ≥5 years] and poor (DFS, <5 years) prognoses was analyzed. The clinicopathological factors of the 341 lymph node-negative breast cancer patients were determined. The 5-year DFS and overall survival rate (OS) in patients >35 years old was higher as compared with those of patients under the age of 35. Tumor size significantly affected the 5-year DFS. Patients with smaller tumors (≤2 cm) had a significantly higher DFS rate as compared with patients with larger tumors (>2 cm). Estrogen receptor (ER)-positive patients had a significantly higher 5-year DFS and OS rate as compared with ER-negative patients. By contrast, there were no significant differences in the 5-year DFS and OS rates between progesterone receptor-positive and -negative patients. The 5-year DFS and OS rates were significantly higher in patients treated with adjuvant hormone therapy, as compared with patients without hormone therapy. The expression of HER2 protein was higher in patients with a poor prognosis as compared with those with a good prognosis; however, there were no differences in the protein expression of CCND1 and TOP2A between patients with a good and poor prognosis. The results of quantitative polymerase chain reaction showed that the gene expression of HER2 and CCND1 was higher in patients with a poor prognosis as compared with that in patients with a good prognosis. TOP2A gene expression was not significantly different between patients with a poor and good prognosis. The age at diagnosis, tumor size, ER status and hormone therapy were associated with prognosis in patients with lymph node-negative breast cancer. The molecular biomarker, HER2, but not CCND1 or TOP2A, may be a critical factor for predicting prognosis.