sentence: Combination chemotherapy with gemcitabine ( Gem ) , doxorubicin ( Dox ) , and paclitaxel ( Pac ) ( GAT ) has been considered attractive as first-line treatment in metastatic breast cancer .
paragraph: Evaluation of a gemcitabine-doxorubicin-paclitaxel combination schedule through flow cytometry assessment of apoptosis extent induced in human breast cancer cell lines.  Combination chemotherapy with gemcitabine ( Gem ) , doxorubicin ( Dox ) , and paclitaxel ( Pac ) ( GAT ) has been considered attractive as first-line treatment in metastatic breast cancer . We compared the potential of various schedules of GAT to induce apoptosis on MDA-MB-231, MCF7, and T47D human breast cancer cell lines. The extent of apoptotic induction was analyzed by flow cytometry with 7-aminoactinomycin D (7AAD) staining. Differences between various schedules in terms of apoptotic induction were statistically significant (P < 0.05). The most effective apoptotic induction regimen was achieved by the sequence: Dox for 16 h followed by Pac + Gem. Schedules employing a 16-h interval between drug administrations induced higher levels of apoptosis in human breast cancer cell lines compared with schedules using a 4-h interval. The therapeutic efficacy of the experimental results shown in this paper has been clinically corroborated in a phase II trial in metastatic breast cancer patients.