Holger Eidtmann

PURPOSE: The exact definition of pathologic complete response (pCR) and its prognostic impact on survival in intrinsic breast cancer subtypes is uncertain. METHODS: Tumor response at surgery and its association with long-term outcome of 6,377 patients with primary breast cancer receiving neoadjuvant anthracycline-taxane-based chemotherapy in seven randomized trials were analyzed. RESULTS: Disease-free survival (DFS) was significantly superior in patients with no invasive and no in situ residuals in breast or nodes (n = 955) compared with patients with residual ductal carcinoma in situ only (n = 309), no invasive residuals in breast but involved nodes (n = 186), only focal-invasive disease in the breast (n = 478), and gross invasive residual disease (n = 4,449; P < .001). Hazard ratios for DFS comparing patients with or without pCR were lowest when defined as no invasive and no in situ residuals (0.446) and increased monotonously when in situ residuals (0.523), no invasive breast residuals but involved nodes (0.623), and focal-invasive disease (0.727) were included in the definition. pCR was associated with improved DFS in luminal B/human epidermal growth factor receptor 2 (HER2) -negative (P = .005), HER2-positive/nonluminal (P < .001), and triple-negative (P < .001) tumors but not in luminal A (P = .39) or luminal B/HER2-positive (P = .45) breast cancer. pCR in HER2-positive (nonluminal) and triple-negative tumors was associated with excellent prognosis. CONCLUSION: pCR defined as no invasive and no in situ residuals in breast and nodes can best discriminate between patients with favorable and unfavorable outcomes. Patients with noninvasive or focal-invasive residues or involved lymph nodes should not be considered as having achieved pCR. pCR is a suitable surrogate end point for patients with luminal B/HER2-negative, HER2-positive (nonluminal), and triple-negative disease but not for those with luminal B/HER2-positive or luminal A tumors.

BACKGROUND: Ovarian suppression plus tamoxifen is a standard adjuvant treatment in premenopausal women with endocrine-responsive breast cancer. Aromatase inhibitors are superior to tamoxifen in postmenopausal patients, and preclinical data suggest that zoledronic acid has antitumor properties. METHODS: We examined the effect of adding zoledronic acid to a combination of either goserelin and tamoxifen or goserelin and anastrozole in premenopausal women with endocrine-responsive early breast cancer. We randomly assigned 1803 patients to receive goserelin (3.6 mg given subcutaneously every 28 days) plus tamoxifen (20 mg per day given orally) or anastrozole (1 mg per day given orally) with or without zoledronic acid (4 mg given intravenously every 6 months) for 3 years. The primary end point was disease-free survival; recurrence-free survival and overall survival were secondary end points. RESULTS: After a median follow-up of 47.8 months, 137 events had occurred, with disease-free survival rates of 92.8% in the tamoxifen group, 92.0% in the anastrozole group, 90.8% in the group that received endocrine therapy alone, and 94.0% in the group that received endocrine therapy with zoledronic acid. There was no significant difference in disease-free survival between the anastrozole and tamoxifen groups (hazard ratio for disease progression in the anastrozole group, 1.10; 95% confidence interval [CI], 0.78 to 1.53; P=0.59). The addition of zoledronic acid to endocrine therapy, as compared with endocrine therapy without zoledronic acid, resulted in an absolute reduction of 3.2 percentage points and a relative reduction of 36% in the risk of disease progression (hazard ratio, 0.64; 95% CI, 0.46 to 0.91; P=0.01); the addition of zoledronic acid did not significantly reduce the risk of death (hazard ratio, 0.60; 95% CI, 0.32 to 1.11; P=0.11). Adverse events were consistent with known drug-safety profiles. CONCLUSIONS: The addition of zoledronic acid to adjuvant endocrine therapy improves disease-free survival in premenopausal patients with estrogen-responsive early breast cancer. (ClinicalTrials.gov number, NCT00295646.)