Table 6. Standard Adjuvant Chemotherapy Regimens for Stage I, II, IIIA, and Operable IIICHER2/neuNon-Overexpressing Breast Cancer continued...
The role of bisphosphonates as part of adjuvant therapy for early stage breast cancer is unclear. The ABCSG-12 (NCT00295646) trial was a 2 × 2 factorial-design randomized trial that assigned 1,803 premenopausal patients with ER+ breast cancer to receive ovarian function suppression with goserelin and tamoxifen versus goserelin and anastrozole. These patients then underwent a second randomization to receive zoledronic acid (4 mg intravenously every 6 months) versus no zoledronic acid.[Level of evidence: 1iiA] There was no significant difference in DFS between the anastrozole and tamoxifen groups. However, the addition of zoledronic acid to endocrine therapy, as compared with endocrine therapy without zoledronic acid, resulted in a relative reduction of 36% in the risk of disease progression (HR, 0.64; P = .01) but did not significantly reduce the risk of death.
While bisphosphonates appear to improve DFS in a population with low-to-intermediate-risk breast cancer, this benefit does not appear to be seen in all patients with breast cancer. The AZURE trial was a randomized, phase III trial that assigned 3,660 patients with stage II or III breast cancer to receive chemotherapy and/or hormone therapy with or without zoledronic acid.[Level of evidence: 1iiA] At a median follow-up of 59 months, there was no significant benefit in the DFS in both groups (77% in each group; HR, 0.98; P = .79). OS was also similar, at 85.4% in the zoledronic acid group and 83.1% in the control group (adjusted HR, 0.85; P = .07).
Based on the conflicting results of these trials, the exact role for bisphosphonates in adjuvant therapy for breast cancer is controversial. An ongoing phase III trial (NCT01077154) is examining the activity of the bone-modifying agent, denosumab, in stage II and III breast cancer.
Several phase III, clinical trials have addressed the role of the anti-HER2/neu antibody, trastuzumab, as adjuvant therapy for patients with HER2-overexpressing cancers.
In the HERceptin Adjuvant (HERA) (BIG-01-01 [NCT00045032]) trial, which is the largest study (5,090 patients), trastuzumab was given every 3 weeks within 7 weeks of the completion of primary therapy that included an anthracycline-containing chemotherapy regimen given preoperatively or postoperatively plus or minus locoregional radiation therapy.[Level of evidence: 1iiA] Although the results of the comparison of 1 year versus 2 years of trastuzumab have not been released yet, there are available data for 3,387 patients (1,694 in the 1-year trastuzumab arm and 1,693 in the observation arm). Of these patients, the median age was 49 years, about 33% had node-negative disease, and nearly 50% had hormone receptor (ER and PR)-negative disease. Patients who were treated with 1 year of trastuzumab experienced a 46% lower risk of a first event (hazard ratio [HR], 0.54; 95% CI, 0.43–0.67; P < .001), corresponding to an absolute DFS benefit of 8.4% at 2 years (95% CI, 2.1–14.8). The updated results at 23.5 months' follow-up showed an unadjusted HR for the risk of death with trastuzumab compared with observation of 0.66 (95% CI, 0.47–0.91; P = .0115), corresponding to an absolute OS benefit of 2.7%. There were 218 DFS events reported with trastuzumab compared with 321 DFS events reported with observation. The unadjusted HR for the risk of an event with trastuzumab was 0.64 (0.54–0.76; P < .001), corresponding to an absolute DFS benefit of 6.3%.