The management of individual breast cancers

The hypothesis that the slope due to shrinkage in response to treatment of a tumour reflects its histological composition has been confirmed in 196 primary breast cancers, as was also the previously observed relationship between slopes and treatments which generated them. The further hypothesis was therefore that histological grade should predict appropriate treatment. This thesis was examined in 98 patients where the response to primary systemic therapy was monitored by calliper measurement. Treatment started with sequential single cytotoxic agents and hormones, reserving weekly combination therapy for rapidly growing tumours which did not shrink in response to single agents (including hormones): Measurement Based Sequential Therapy (MBST). Some shrinkage occurred in 90% of tumours. Most grade I and II tumours shrank in response to single agents but most grade III tumours, none of which shrank in response to hormones, needed the more intensive treatment. Shrinkage directly attributable to tamoxifen was seen in 33% of tumours; 17% grew. From the distribution of representative slopes we calculate that up to 40% of tumours might not shrink in response to conventional chemotherapy at 3–4 weekly intervals and that 5% of tumours would not shrink on weekly treatment. Long-term local control was not achieved by primary systemic therapy alone although the local situation was improved in most cases. Surgery and/or radiotherapy was the final local management; no local treatment was an option where metastatic or intercurrent life-threatening disease predominated. We conclude that histological grading predicts both the intrinsic rate of shrinkage and the appropriate treatment by which that may be achieved. The prediction may be tested by primary systemic therapy enabling ineffective drugs to be discarded and treatment to be tailored to the individual patient.