Annual mammography at age 45-49 years and biennial mammography at age 50-69 years: comparing performance measures in an organised screening setting.

Objective: To compare the results of 5 years of annual mammography screening at age 45-49 with the results of 5 years of biennial screening at age 50-54 and 55-69.

Methods: In an Italian screening programme, data from 1,465,335 mammograms were analysed. Recall rates, invasive assessment rates, surgical biopsy (including excisional biopsy and definitive surgical treatment) rates, and cancer detection rates were calculated for the first screen (first) and, cumulatively, for the second and subsequent screens (second+).

Results: The rate ratios between younger women and the two groups of older ones were (in parentheses, original figures per 1000 mammograms if not otherwise specified): recall rate: first 1.11 (103.6 vs. 93.5) and 1.11 (vs. 93.2), second+ 2.10 (208.9 vs. 99.7) and 2.77 (vs. 75.5); invasive assessment rate: first 0.94 (23.0 vs. 24.5) and 0.94 (vs. 24.6), second+ 1.63 (35.8 vs. 22.0) and 1.56 (vs. 23.0); surgical biopsy rate: first 0.68 (5.9 vs. 8.6) and 0.45 (vs. 13.2), second+ 1.35 (11.5 vs. 8.5) and 0.88 (vs. 13.0); total detection rate: first 0.63 (4.3 vs. 6.7) and 0.37 (vs. 11.7), second+ 1.30 (8.9 vs. 6.8) and 0.74 (vs. 12.0); total positive predictive value of surgical biopsy: first 0.93 (72.8% vs. 78.0%) and 0.82 (vs. 88.9%), second+ 0.96 (77.2% vs. 80.5%) and 0.83 (vs. 92.7%).

Conclusion: Younger women experienced two to threefold higher cumulative recall rates at second+ screens and limited differences in surgical biopsy rate. Albeit encouraging, these results must be completed with further investigation, especially on interval cancer incidence.

Key Points: • At repeated screens, cumulative recall rate was two- to threefold higher for younger women. • Differences in cumulative surgical referral and surgical biopsy rates were moderate. • Differences in positive predictive value of surgical biopsy were particularly small.