Breast cancer screening for women aged 40 to 49 years--what does the evidence mean for New Zealand?

AIM To review the evidence on the benefits, harms and costs of breast cancer screening for women aged 40 to 49 years in New Zealand. METHODS A review of the two most recently published meta-analyses of breast cancer screening, combined with a web-based literature search and review. RESULTS The meta-analyses demonstrated that mammography reduces breast cancer mortality among women aged 40 to 74 years. Benefit is greatest, and harms are lowest, for women aged over 50. Cost-effectiveness is also greater for women aged over 50. CONCLUSION The risks of developing and dying of breast cancer are continuous variables that increase with age. The United Kingdom Age Trial will provide further important evidence to guide policy on breast screening for women aged 40 to 49. The most recent reports of this trial suggest a smaller reduction in predicted deaths than observed in many other studies that included women below the age of 50, and less than in either of the meta-analyses reported in this article. Any further lowering of the age range of BSA should be informed by the results of this trial as well as other high quality studies that examine both the benefits and harms of breast screening for women aged 40 to 44.