ABSTRACT
Breast cancer is the most common form of cancer among women in industrialised countries. In the UK, breast cancer accounts for 15% of all new cancer cases and is the most common cancer. A range of associations have been linked with the development of primary breast cancer. Many of these are inherent and cannot be modified by individual behaviour. The Collaborative Group on Hormonal Factors in Breast Cancer brought together and re-analysed the worldwide epidemiological evidence on the association between breast cancer risk and the use of hormonal contraceptives, and produced a number of conclusions. Breast cancer risk is lower the younger childbearing begins, the relative risk declining by 3% for each year earlier that the first child is born. Obesity is a universal health concern in both developed and developing countries. An increasing proportion of all populations are obese or overweight and approximately 65 million additional adults who are obese are projected for the United States by 2030.
