As breast cancers are diagnosed at increasingly early stages, and there is little biological rationale for mastectomy in most patients, breast conservation is likely to be practised with increased frequency in the future. Newer breast imaging techniques, particularly magnetic resonance imaging (MRI), should contribute to improved pretherapy planning, both aiding in the selection of patients for conservation approaches, and estimating the residual tumour burden following minimally invasive surgical interventions. Image-guided tumour mapping may permit local treatment to be individualised, most importantly allowing definition of subgroups not requiring treatment directed at the whole breast. Moreover. interventional radiology opens new possibilities for focalised treatments, which may come to be employed in the management of small lesions. The increasing use of primary chemo- or chemoendocrine therapy will also lend to favour the option of breast conservation. Functional imaging techniques, including MRI, may prove valuable in the assessment of response to medical therapy, allowing more individualised use of radiotherapy and surgery. Technical progress and the development of biological response modifiers may further improve the therapeutic ratio associated with radiation treatment. (C) 2000 Elsevier Science Ltd. All rights reserved.