Introduction

Abstract

The majority of patients with cancer present to their doctor when their disease has already spread. For these patients, surgical resection of the primary tumour or local radiotherapy may control the tumour, but cure of the metastatic disease by these treatments is impossible. Thus, for the majority of cancer patients, cure of the disease depends either upon earlier diagnosis — tumours being treated when local treatments may be curative — or upon the development of some systemic treatment to kill metastatic tumour cells.