Proliferative activity, histological grade and benefit from adjuvant chemotherapy in node positive breast cancer

The influence of S-phase fraction (SPF), measured by DNA flow cytometry, and histological grade on outcome following adjuvant chemotherapy was analysed for 214 patients with node positive breast cancer treated at Guy's Hospital who were entered into the Guy's/Manchester trial of combination chemotherapy with cyclophosphamide/methotrexate/5-fluorouracil (CMF) vs. no adjuvant treatment. Adjuvant CMF significantly improved relapse-free survival (RFS) for premenopausal patients whose tumours had an SPF of 10% or less (control vs. CMF, P = 0.05) and premenopausal patients whose tumours had an SPF over 10% (control vs. CMF, P = 0.003). No significant improvement in RFS attributable to CMF was seen for either subgroup of postmenopausal patients. When patients were divided into subgroups based on histological grade of tumour, an improvement in RFS attributable to CMF was seen for premenopausal patients with well differentiated (grade 1 or 2) tumours (control vs. CMF, P = 0.03) and premenopausal patients with poorly differentiated (grade 3) tumours (control vs. CMF, P = 0.006). Again, no improvement in RFS was noted for any subgroup of postmenopausal patients defined by tumour grade.