CANCERS DETECTED AND INDUCED IN MAMMOGRAPHIC SCREENING - NEW SCREENING SCHEDULES AND YOUNGER WOMEN WITH FAMILY HISTORY

The numbers of cancers detected and induced in breast screening progra mmes are examined for two-view screening, and for a 2 year screening i nterval, in contrast to the single view screening at a 3 year interval of the UK Breast Screening Programme up until early 1995. Two-view sc reening is also considered for the 1 year interval and age range of th e current UK age trial (40-47 years). The corresponding figures for sc reening of groups having a family history of breast cancer are calcula ted and discussed. Breast cancer induction data are taken from Nationa l Radiological Protection Board publications. Cancer detection rates a re based on observed rates where available, and calculated rates other wise. The results of calculations indicate cause for concern if screen ing is to be extended below the age of 30 years (or below 35 years in certain categories), or below 40 years of age if family history groups are shown in the future to have a generally increased susceptibility to ionizing radiation. The importance of restricting dose to 2 mGy per film (mean glandular dose for a standard breast thickness of 4.5 cm) is stressed, together with the need to maintain maximum image quality. This is especially true for the family history groups, who should onl y be screened in centres within established screening programmes, or i n centres with equally strict quality control procedures.