III. The Role of Histology in the Treatment of Breast Cancer

The importance of an accurate classification when attempting to assess the role of radiotherapy in breast cancer has been stressed. It is suggested that the difficulty in evaluating any form of treatment in this disease may be largely due to neglect of the nature of the tumour itself. The primary tumours of 1002 cases of carcinoma of the breast have been divided into three grades of malignancy depending upon simple histological criteria and a good correlation with prognosis has been obtained. Five-year results are presented for the entire series and ten-year results for 633 patients. A classification based upon the stage of the disease and the histological grade of malignancy probably provides the most accurate guide to prognosis available at the present time. This may assist in the search for the most suitable treatment for individual patients according to the nature and extent of the growth. The influence of irradiation on the different types of tumour is being studied and illustrations are given of initial clinical and histological responses in the three grades of malignancy. Equally dramatic changes are seen in some well-differentiated tumours of low grade malignancy, as well as in examples of anaplastic growths of high malignancy.