A COMPARATIVE AUDIT OF PREVALENT, INCIDENT AND INTERVAL CANCERS IN THE AVON BREAST SCREENING-PROGRAM

The 4th year of the Avon breast screening programme comprises two dist inct groups: those called for screening for the first time (prevalent group) and those who were initially screened 3 years earlier (incident group). The cancer detection rate, stage of disease and rate of inter val cancers in these patients have been compared. For the prevalent gr oups of year 1 and year 4 there was no statistically significant diffe rence in the cancer detection rate, proportion of small tumours or nod e positivity. For the prevalent and incident groups of year 4, there w as no statistically significant difference in the cancer detection rat e or proportion of small tumours. There were significantly fewer node- positive tumours in the incident group (5/45 vs 8/23; P < 0.05). Fifty -six interval cancers presented in the 3-year period between years 1 a nd 4 of screening; 28 (50%) after 24 months. The screening programme m ay result in tumours being detected at an earlier stage, but this may be offset by the high rate of interval cancers. This suggests that the time between screens may need to be reduced to 2 years.