ABSTRACT
Breast cancer is the commonest malignancy in women worldwide and the incidence is rising. In 2014, 55,200 new cases of breast cancer were diagnosed in the UK, accounting for 31% of all female cancer diagnoses; in the US, there were an estimated 252,710 new cases in 2017 (1,2). Incidence rates in the UK have increased by nearly 20% since the 1990s and are projected to reach 210 per 100,000 women by 2035 (1). There are marked geographical variations, with much higher rates in developed countries. The low incidence previously reported in Asia is now rising, whereas in the US, the incidence rate is beginning to plateau (3). Within Europe, incidence rates decrease from north to south and positively correlate with per capita income. In migrants, the incidence rate converges with that of the indigenous population within two generations, indicating the importance of environmental factors (4). Increasing incidence trends reflect changing prevalence of risk factors, the introduction of mammography screening programmes from the late 1980s, and better diagnostics and data collection.
