Prospective randomized trial of 5-fluorouracil, doxorubicin, and cyclophosphamide (FAC) versus paclitaxel and FAC (TFAC) in patients with operable breast cancer: impact of taxane chemotherapy on locoregional control

A previous randomized trial (CALGB 9344/Intergroup 0148) compared four cycles of adjuvant doxorubicin/cyclophosphamide (AC) to four cycles of AC plus four cycles of paclitaxel (AC + T) and demonstrated that the addition of paclitaxel improved locoregional control (LRC) in patients with node-positive breast cancer. However, it could not be determined whether it was the paclitaxel or the increased duration of chemotherapy that led to this improvement. The present study aimed to analyze whether the addition of paclitaxel to a doxorubicin-based regimen improves LRC in a cohort of patients who all received eight total cycles of chemotherapy. Five hundred eleven women with operable breast cancer were randomized on a single-institution prospective trial to receive 5-fluorouracil, doxorubicin, cyclophosphamide (FAC) × 8 cycles (n = 252) or FAC × 4 cycles plus paclitaxel × 4 cycles (TFAC) (n = 259). Rates of LRC and overall survival (OS) were analyzed. Median follow-up was 124 months (range 5–167 months). The 10-year LRC rate was 92.6 versus 93.1% in the FAC versus TFAC arms, respectively (P = 0.26). The LRC between treatment arms did not differ when analyzed by locoregional treatment group: breast conservation therapy (BCT), mastectomy alone (M), and mastectomy + radiation (M + RT). The 10-year LRC rates were 95.1% (FAC) versus 91.2% (TFAC) after BCT (P = 0.98), 89.5% (FAC) versus 93.4% (TFAC) after M (P = 0.24), and 94.7% (FAC) versus 96.5% (TFAC) after M + RT (P = 0.59). Additionally, there was no difference in OS between the treatment arms, with 10-year OS rates of 78.4% (FAC) versus 81.7% (TFAC) (P = 0.93). The addition of paclitaxel to a doxorubicin-based regimen had no impact on LRC, regardless of the type of local therapy received. Historically inferior LRC with AC chemotherapy alone versus AC + T may have been due to an inadequate duration of systemic therapy and not due to the absence of paclitaxel.