Abstract A consecutive series of 457 patients with breast cancer is reviewed. Tumor size, duration, and extent of nodal involvement are very important factors in prognosis. We continue to believe that so-called radical mastectomy is the surgical procedure of choice in suitable patients because of the finding of 30 per cent positive nodes in clinically negative axillas. Although this disease may follow an anticipated pattern, it remains a classic prototype of one in which the ultimate outcome depends on the balance between the virulence of the cancer cell and the resistance of the individual patient to that tumor cell. When we understand this mechanism better, real progress in treatment will become a reality.