The role of chemotherapy for node-negative breast cancer

Approximately 25% of women with early stage breast cancer and negative axillary nodes will eventually die of metastatic disease. Some studies have shown a recurrence rate of 40% or more at 10 years in this relatively good prognostic group. The incidence of breast cancer continues to increase approximately 1% per year with a great increase in the frequency of early stage disease (particularly in situ carcinoma). The increased use of mammography and physical examination with appropriate follow-up will increase the frequency of diagnosis of node-negative patients compared with those with more advanced stages. Women with positive axillary nodes who are premenopausal benefit from adjuvant chemotherapy, whereas those who are postmenopausal have shown a clear reduction in mortality when treated with tamoxifen. It is even more reasonable to speculate that women with node-negative disease could have an even greater benefit from adjuvant therapy because they have a lower tumor burden at the time of diagnosis. Compared with earlier clinical adjuvant trials, more recent studies (1981-89) have shown a disease-free survival advantage for node-negative breast cancer patients treated with adjuvant chemotherapy. Hopefully, the differences noticed in disease-free survival will show a similar survival advantage with further observations. The results of these clinical trials suggest that adjuvant chemotherapy may be of benefit to patients with node-negative disease but do not support the contention that all node-negative patients with breast cancer should receive adjuvant chemotherapy. Some prognostic subgroups (tumor size greater than 2 cm) have shown an overall 10-year survival rate of 92% for women who have not received adjuvant therapy. The benefits versus toxicities of adjuvant therapy should be carefully evaluated before the initiation of adjuvant therapy.