To determine the predictive value of HER2 expression for the selection of adjuvant chemotherapy (antracycline or nonantra-cycline based) in patients with breast cancer.

Medical records of primary breast cancer patients treated at the Oncology Center of Latvia from January 2002 to August 2005 were retrospectively reviewed. One hundred and ninety-two patients with histopathologically confirmed breast cancer, who had undergone radical surgery and adjuvant chemotherapy (CT), were identified. Tumor characteristics were: ER+ in 62.5%, ER- in 37.5%, HER2-positive (3+ by IHC) in 30.2% (58 patients), HER2-negative (0, 1+) in 54.7% (105 patients); patients with score 2+ (15.1%, 29 patients) were excluded from analysis. Staging: I (20.8%), II (51%), III (29.2%); 43.8% patients were node negative, 56.2% were node positive. Median age at diagnosis was 52.4 (30–75) years.

Antracycline-based CT (FAC or FEC) was received by 62.9% patients in the HER2-negative group and 41.4% in the HER2-positive group, nonantracycline based (CMF) CT in 37.1% and 58.6% respectively. The median follow-up time was 21.3 (6.3–51.7) months. A total of 25.2% tumor recurrences were observed. Median time to relapse was 12.5 (1.4–34) months. In the HER2-positive group the relapse rate was 20.8% in patients receiving antracycline-based CT versus 29.4% in patients receiving nonantracycline-based CT (P = 0.09). In the HER2-negative group the relapse rate was 33.3% in patients receiving antracycline-based CT versus 15.8% in patients receiving nonantracycline-based CT (P = 0.2). The subgroup of patients with HER2-negative, ER-negative tumors had the worst prognosis (relapse rate 45%) regardless of the CT received.

In patients with HER2 overexpression, antracycline-based CT produced a significantly lower relapse rate when compared with nonantracycline-based CT. In HER2-negative patients there was no benefit from antracycline-based CT compared with nonantracycline-based CT. However, a longer follow-up period is needed to confirm the results.