Background: To correlate age-standardized rates [ASRs] of DCIS, BrCaINV and BrCaMOR, separately for ages <50 vs >50. British Columbia [BC] is known for earlier introduction, tighter adherence to, and more uniformity of ScreenMam than the Atlantic Provinces [AP]. Methods: Annual age-specific rates [ASRs] of DCIS, BrCaINV, and BrCaMOR were obtained for 17 five-year age groups (years 0-4 to 85+) in BC and AP, and averaged over 5-year1970-1974 to 2005-2009 periods [Lustrum], separately for ages <50 and >50. BrCaINV and BrCaMOR rates were expressed in percentages, relative to 1970-74 average. Data were obtained from Canada Public Health Agency and Canada Ca Registry database at Statistics Canada. Results: See Tables. Conclusions: DCIS: Rates are substantially increased since 1970s in both regions. For ages >50, rate stabilization is seen after 2000s, particularly in BC where the rate decrease is seen after 2005. BrCaINV: In both regions, rates for ages <50 have been stable. For ages >50, rates are initially increasing and then decreasing, with reduction observed to a lower extent in BC, and much earlier than in AP BrCaMOR: For both age groups, rate decrease is more substantial in BC than AP. Difference is particularly evident for ages >50, with reduction in BC observed at least a decade earlier, and to a much lower degree. SUMMARY: Levelling or decrease of DCIS rates in regions with more adherent ScreenMam is a new observation which may antedate a more substantial delayed rate reduction of both BrCaINV and BrCaMOR. Earlier diagnosis & therapy of less resistant BrCa lesions, as enabled by ScreenMam, are the likely causes for these outcome improvements.