Radiation Therapy in Breast Cancer: Optimal Combination of Technical Factors; Analysis of Five-Year Results

Although both mastectomy and radiation have been used in the treatment of breast cancer for over half a century, there is still no unanimity among surgeons or radiotherapists as to the value of such treatment in general, much less as to the relative merits of the two modalities and the various technical differences in the application. According to some authorities (49, 58), it is doubtful whether the average survival of patients with breast cancer can be improved by any form of therapy currently available, be it radical surgery or radiation therapy, although the palliative value of treatment for the locally advanced or metastatic stages of the disease is generally accepted. Whether a combined procedure can achieve more than either modality alone or, more specifically, the extent to which radiation can improve upon the overall salvage rate with surgery alone, remains obscure. Before any form of therapy can be assessed, therefore, it is necessary to define its objectives and limitations. There is some evidence (54) that the survival time is significantly prolonged in treated patients as compared with an untreated series. The average duration of life in untreated cases is approximately forty months from the onset of symptoms (10, 24, 30, 54, 65, 68) and the five-year survival rate is in the region of 16 to 20 per cent (1, 34). In treated series the overall five-year survival averages around 35 per cent, ranging from 55 per cent for early cases to 15 per cent for later stages (6, 57, 62, 67). It is an interesting fact that, in spite of the widely different surgical procedures employed, including radical and supraradical mastectomies, local mastectomy with or without axillary node dissection, and even simple excision of the tumor alone, and the varied radiotherapy techniques and dosages, the five-year survival rates, when corrected for the relative proportions of early and late cases, are essentially the same at different centers (6, 57). The survival rate has also remained fairly constant, irrespective of technical advances over the years. It seems unlikely at present that any further developments in technique, either in surgery or in radiation therapy, could improve upon these figures substantially. The outcome is determined in most instances by the degree of dissemination of the tumor and is independent of the exact surgical or radiotherapeutic measures employed (57, 58). A significant proportion of surviving patients will have locally persistent or recurrent cancer in the chest wall or regional lymph nodes. The question then arises as to whether improved techniques can reduce the local recurrence rate, without adversely affecting the overall five-year survival. If any particular radiotherapeutic procedure can achieve this, then radiation is justifiably applied as a radical treatment or adjunct in the management of breast cancer, in addition to its obvious role in palliation of advanced disease.