Breast Screening: Process and Outcome

Abstract

The evaluation of any screening programme is of great importance because resources devoted to screening must be justified and the impact of screening on survival, mortality and other indices demonstrated. Such evaluation is likely to require long term commitment (e.g. as in the evaluation of breast screening). The anticipated reduction in breast cancer mortality owing to screening is expected to take 10 years or more from the introduction of the programme to become evident. A number of other measures are, therefore, necessary to predict the impact on mortality, including: breast cancer detection rates and stage distribution at prevalence and incidence screening; detection rates of small invasive cancers; incidence rate of advanced cancers; and the incidence and attributes of interval cancers [1]. An increasing proportion of cancers in the age group that is eligible for breast screening are screen detected and what is evident is that many are very small; over half of the invasive cancers detected by the NHS Breast Screening Programme are 15 mm or less across [2]. There are, of course, national clinical trials looking at the treatment of small invasive and in situ cancers and, in particular, the appropriate adjuvant therapy that should be offered. Apart from the various clinical trials, annual audits of surgical data for the entire UK breast screening programme are undertaken by the British Association of Surgical Oncology Breast Group. These include the variation in treatment with tumour size [3]. Information on outcomes of screen-detected cancers after various treatment options is collected at various centres and the paper by Magee et al. describes the outcomes for women undergoing radiotherapy after breast conserving surgery [4]. Such information is a welcome addition to the knowledge required for the successful management of the disease and one can only echo the plea by the authors for such studies to continue in order to provide further information from