Biologic tumor markers, lymph node status, and decision about adjuvant chemotherapy for breast cancer.

The reasons to perform axillary dissection for breast cancer are to determine lymph node status for prognosis and adjuvant chemotherapy treatment decisions. Some have questioned whether this knowledge actually affects such decisions in some patients. A retrospective review was done on 30 patients with invasive breast cancer whose tumors were further evaluated by tumor size, estrogen and progesterone receptor status, ploidy, S-phase fraction, DNA index, and lymph node status. All patients were treated either with lumpectomy/axillary dissection and postoperative radiation therapy or with modified radical mastectomy. A stepwise logistic regression was done to determine which factors were statistically significant in the decision to offer adjuvant cytotoxic chemotherapy by independent medical oncologists (endocrine therapy was not an end point in this study). Only high S-phase fraction (above 5 per cent) was an independent predictor of subsequent administration of cytotoxic chemotherapy (P < 0.0001). The sensitivity and specificity of high S-phase fraction leading to chemotherapy was 100 per cent. There was a high concordance between S-phase fraction and lymph node status, with high S-phase being predictive of positive lymph nodes (P = 0.008), and positive lymph nodes (P = 0.008) and estrogen receptor-negative status (P = 0.034) predictive of high S-phase fraction. When S phase was excluded from analysis, the lymph node status (P < 0.0001) and DNA index (P = 0.03) were independent predictors of subsequent chemotherapy. In the subset of patients with high S-phase fraction, knowledge of lymph node status did not affect decisions about adjuvant cytotoxic chemotherapy. Axillary dissections may be avoided in these patients, decreasing morbidity and costs. However, in the absence of knowledge of S-phase fraction, knowledge of lymph node status becomes important in determining need for chemotherapy.