The long-term results of this trial of adjuvant combination chemotherapy confirm our preliminary observations of the effectiveness of the treatment in women with node-positive breast cancer.

Current findings indicate that primary chemotherapy can be safely administered in women with large tumors (>5.0 cm) and can allow breast-sparing surgery in a high fraction of patients (62%). However, to assess effectively the worthiness of this approach on long-term results, properlyconceived large randomized studies with newer and more effective drug regimens are warranted.

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Objective To assess the long term effectiveness of adjuvant treatment with cyclophosphamide, methotrexate, and fluorouracil (CMF) in patients with operable breast cancer at risk of relapse, on the basis of three successive randomised trials and one observational study conducted from June 1973 to December 1980. Design Cohort study. Setting Istituto Nazionale Tumori in Milan, Italy. Main outcome measures Relapse free and overall survival, measured by univariate and multivariate analyses. Results After a median follow up of 28.5 years for the initial study, adjuvant CMF was found to reduce the relative risk of relapse significantly (hazard ratio 0.71, 95% confidence interval 0.56 to 0.91, P = 0.005) and death (0.79, 0.63 to 0.98, P = 0.04). Administration of CMF for 12 cycles does not seem superior to a shorter administration of six cycles. In the node negative and oestrogen receptor negative trial, intravenous CMF significantly reduced the relative risk of relapse of disease (0.65, 0.47 to 0.90, P = 0.009) and death (0.65, 0.47 to 0.92, P = 0.01) at a median follow up of 20 years. Conclusions When delivered optimally, CMF benefits patients at risk of relapse of distant disease without evidence of detrimental effects in any of the examined subgroups.

At least two different therapeutically vulnerable proliferative events, resulting in clinical appearance of two metastasis temporally distinct clusters of post-resection cancer recurrence, apparently occur during the administration of adjuvant chemotherapy. Metastases that transpire outside of these temporal windows are refractory to adjuvant therapy. The dynamics of both post-treatment recurrence risk and CMF effectiveness are similar for both pre- and postmenopausal women, suggesting that post-resection mechanisms by which chemotherapy prevents metastases are similar, but of different magnitude in pre- and postmenopausal women. These findings are consistent with a metastasis model that includes tumor dormancy in specific micrometastatic phases (single cells and avascular foci) and with the acceleration of the metastatic process by the surgical resection of the primary breast cancer.