Breast carcinoma stage in relation to time interval since last mammography: a registry-based study. The Romagna...

In the Romagna Region of Italy, mammography screening for breast carcinoma (BC) was implemented as a routine practice in the regular healthcare system. The Romagna Cancer Registry evaluated the effects of self-selection for mammography on the stage of BC at the time of presentation.

Of the 851 invasive BC cases registered in 1989-1991, tumor size (T) was documented for 790 (93%) and lymph node status (N) for 681 (80%). Mammography experience was determined by cross-checks with the radiology files in the area. The Mantel-Haenszel chi-square test stratified by age was used to evaluate the difference in the proportion of advanced BC between subsets of patients diagnosed at increasing time intervals since their most recent mammography and those with no previous examination.

The incidence of T2+/N1+ (T2 or worse and/or lymph node positive) BC was 71% among patients without previous mammography. No advantage was observed for patients diagnosed within 6-12 months of their last mammography (69%). A marked advantage was associated with intervals varying between 12-23 months (45%; P < 0.001) and between 24-35 months (43%; P < 0.001). For longer intervals, the proportion of T2+/N1+ disease stabilized at 56%. For patients with any interval > 5 years (range, 5-22 years; median, 11 years) the relative stage advantage was significant (P = 0.013).

The stage pattern of patients diagnosed with BC 5-22 years after their last mammography suggests that even if health-aware women who volunteered for screening stop undergoing regular mammography, they present for a relatively prompt diagnosis in the event they develop BC.