Background: We evaluated the efficacy of gemcitabine and carboplatin for patients affected by pretreated metastatic breast cancer. A subgroup analysis was performed to evaluate the predictive value of immunohistochemically defined breast cancer subtypes.
Methods: We included human epidermal growth factor 2 (HER-2) negative metastatic breast cancer resistant to previous anthracycline-based and taxane-based chemotherapy, and HER-2 positive metastatic breast cancer with at least two progressions of disease during protracted trastuzumab-based therapy. Treatment consisted of gemcitabine (1000 mg/m(2) intravenous (iv) on days 1 and 8) and carboplatin (area under the curve 5 iv on day 1) applied every 3 weeks.
Results: Forty-two patients were registered. Disease control was 58%, with a median time-to-progression (TTP) of 7 months (range 1-12) and a median overall survival of 10.5 months (range 1-34). Patients were grouped as triple negative (ER and PR negative, HER-2 negative), HER-2 (HER-2 positive, ER and PR negative), luminal B (ER and/or PR positive and either HER-2 positive and/or high Ki67), and luminal A (ER and/or PR positive and HER-2 negative and low Ki67). For luminal A patients, disease control was lower (luminal A 34 vs. others 67%; P = 0.02), TTP was shorter (luminal A 2.4 months vs. others 6.3 months, P = 0.015), and overall survival was shorter (luminal A 7.5 months vs. others 11.7 months, P = 0.034) than for other subtypes.
Conclusions: Gemcitabine and carboplatin are effective for pretreated patients with metastatic breast cancer. Luminal A subtype seems to fare poorly compared with other subtypes. Specific difference in gene expression might account for the different outcome.