Table 6. Standard Adjuvant Chemotherapy Regimens for Stage I, II, IIIA, and Operable IIICHER2/neuNon-Overexpressing Breast Cancer continued...
Adjuvant Chemotherapy 2000s to Present: The role of adding taxanes to adjuvant therapy
A number of trials have addressed the benefit of adding a taxane (paclitaxel or docetaxel) to an anthracycline-based adjuvant chemotherapy regimen. A literature-based meta-analysis of 13 such studies demonstrated that the inclusion of a taxane improved both DFS and OS (DFS: HR, 0.83; 95% CI, 0.79–0.87; P < .0001; OS: HR, 0.85; 95% CI, 0.79–0.91; P < .0001).[Level of evidence: 1iiA] Five-year absolute survival differences were 5% for DFS and 3% for OS in favor of taxane-containing regimens. There were no differences in benefit observed in patient subsets defined by nodal status, hormone receptor status, or age/menopausal status. There was also no apparent difference in efficacy between the two agents. However, none of the studies reviewed involved a direct comparison between paclitaxel and docetaxel.
An Eastern Cooperative Oncology Group–led intergroup trial (E1199 [NCT00004125]) involving 4,950 patients compared, in a factorial design, two schedules (weekly and every 3 weeks) of the two drugs (docetaxel vs. paclitaxel) following standard-dose AC chemotherapy given every 3 weeks.[Level of evidence: 1iiA] There was no difference observed in the overall comparison with regard to DFS of docetaxel to paclitaxel (odds ratio [OR], 1.03; 95% CI, 0.91–1.16; P = .61) or between the 1-week and 3-week schedules (OR, 1.06; 95% CI, 0.94–1.20; P = .33). However, there was a significant interaction between the drug administered and schedule for both DFS (0.003) and OS (0.01). Thus, compared with paclitaxel given every 3 weeks, paclitaxel given weekly improved both DFS (OR, 1.27; 95% CI, 1.01–1.57; P = .006) and OS (OR, 1.32; 95% CI, 1.02–1.72; P = .01). Docetaxel given every 3 weeks was also superior in DFS to paclitaxel given every 3 weeks (OR, 1.23; 95% CI, 1.00–1.52; P = .02), but the difference was not statistically significant for OS (OR, 1.13; 95% CI, 0.88–1.46; P = .25). Docetaxel given weekly was not superior to paclitaxel given every 3 weeks. There was no stated a priori basis for expecting that varying the schedule of administration would have opposite effects for the two drugs. Thus, these results are hypothesis generating and should be confirmed.
A U.S. Intergroup study (CLB-9344) randomly assigned women with node-positive tumors to three dose levels of doxorubicin (60, 75, and 90 mg/m2) and a fixed dose of cyclophosphamide (600 mg/m2) every 3 weeks for four cycles. After AC chemotherapy, patients were randomly assigned for a second time to paclitaxel (175 mg/m2) every 3 weeks for four cycles versus no further therapy, and women with ER-positive tumors also received tamoxifen for 5 years. Although the dose-escalation of doxorubicin was not beneficial, the addition of paclitaxel resulted in statistically significant improvements in DFS (5%) and OS (3%).[Level of evidence: 1iiA] The results of a second trial, the NSABP-B-28 trial, have also been reported. This trial randomly assigned 3,060 women with node-positive breast cancer to four cycles of postoperative AC or four cycles of AC followed by four cycles of paclitaxel. All women older than 50 years, and those younger than 50 years with receptor-positive disease, received tamoxifen. In this trial, DFS was significantly improved by the addition of paclitaxel (hazard ratio [HR], 0.83; 95% CI, 0.72–0.96; P = .006; 5-year DFS = 76% vs. 72%). The difference in OS was small (HR, 0.93), however, and not statistically significant (P = .46).[Level of evidence: 1iiA]