Recent trends of in situ carcinoma of the breast and mammographic screening in the Florence area, Italy

Objectives: The study analyzes the relationship between the incidence trend s of breast carcinoma in situ (CIS) and the spread of mammography screening in the Italian area of Florence (about 608,000 female residents). Setting: In this area, since the seventies, a mammographic screening by per sonal invitation was performed by the Center for Cancer Prevention (CSPO) i n some rural municipalities. After 1990, the municipality of Florence and o ther municipalities were involved in the screening. Methods: The study included all cases of female breast carcinomas in situ r eported to the population-based Tuscany Cancer Registry between 1985 and 19 95. On the basis of information from the CSPO files, the cases were categor ized into: "screen-detected", "self-referrals", and "other" (CSPO cases dia gnosed in symptomatic women or at periodic check up after breast cancer plu s hospital cases). Results: Overall, 332 women with breast carcinoma in situ (CIS) were regist ered between 1985 and 1995. The CIS incidence rate increased from 2.39/100, 000 women in 1985-87 to 6.22/100,000 in 1994-95. The largest increase was o bserved for the ductal carcinoma in situ (2.9 times) and in women aged 50-6 9 years (3.8 times). In this age group, cases diagnosed at the screening by personal invitation accounted for 69% of the rise in CIS incidence. The pr oportion of mastectomy lowered from 41% before 1990 to 25% after 1990. Conclusion: In the Florence area the CIS incidence trend, showing a marked increase beginning in 1991, was mainly explained by the spread of the mammo graphic screening by personal invitation. The period during which mammograp hic screening became widespread coincided with a change in the treatment po licy of breast cancer, with a high proportion of breast conserving surgery also for CIS. Therefore, the rise in CIS incidence rates correlated with th e widespread use of mammographic screening did not substantially increase t he number of women treated by mastectomy.