Adjuvant therapy of primary breast cancer: a review of key findings from the 7th international conference, St. Gallen, February 2001

Abstract

Breast cancer research has developed at a rapid pace over the last decades. Recent discoveries promise to provide individualized treatment options, increased long-term survival for women with breast cancer, and the possibility of moving toward curative intent in the treatment of advanced breast cancer. Age, race, tumor size, histological tumor type, axillary nodal status, standardized pathological grade, and hormone-receptor status are accepted as established prognostic and/or predictive factors for selection of systemic adjuvant treatment of breast cancer. The role of other promising new factors, such as p53 mutations, HER-2 status, plasminogen activator system, histological evidence of vascular invasion, and quantitative parameters of angiogenesis will be determined in ongoing prospective studies. Currently, 5 years' treatment with adjuvant tamoxifen in women with hormone-positive receptor status, is regarded as the optimal duration of treatment. Long-term follow-up on the randomized trials will determine the added benefit of treatment beyond 5 years. Ovarian ablation has shown a reduction in recurrence and death, and the exact role and extent of adjuvant chemotherapy in premenopausal women with hormone-responsive tumors is under discussion. Combination hormonal and chemo-hormonal therapies are also being evaluated. There are no convincing data on the survival impact of tamoxifen as a preventative therapy for breast cancer: longer-term follow-up is required, and the planned meta-analyses in 2005 should help shed light on this issue. Statistically significant benefits have been observed with adjuvant chemotherapy (particularly with anthracycline-containing regimens in premenopausal women) versus no adjuvant chemotherapy. The optimal length of adjuvant anthracycline/cyclophosphamide (AC) regimens needs further evaluation as do randomized comparisons of AC to cyclophosphamide/ doxorubicin/5-fluorouracil (5-FU) and cyclophosphamide/epirubicin/5-FU. Although taxanes promise to provide an additive benefit to adjuvant chemotherapy regimens, the Cancer and Leukemia Group B 9344 and the National Surgical Adjuvant Breast and Bowel Project B-28 studies evaluating paclitaxel in the adjuvant setting have not yet demonstrated statistically significant benefits on disease-free survival and overall survival. In the year 2000, all adjuvant therapy studies conducted by the Co-operative Groups in both node-negative and node-positive disease involve a taxane. High-dose chemotherapy evaluations are still ongoing. The numerous prospective adjuvant therapy trials (hormonal; selective estrogen-receptor modulators; aromatase inhibitors; chemotherapy, involving anthracyclines/taxanes/platinum/trastuzumab; biological factors; elderly women (>70 years); high-risk patients; radiotherapy in 1-3 positive lymph nodes), and neoadjuvant studies might further define the chances to enhance cure rates in the treatment of primary breast cancer.