Changing trends in proportional incidence and net survival of screened and nonscreened breast cancers among women in England

Abstract

Background: Uptake of breast cancer screening has been decreasing in England since 2007, and may increase proportional incidence of nonscreened cancers. However, recent trends in proportional incidence and net-survivals of screened and nonscreened breast cancers are unclear. Methods: We extracted population-based proportional incidence and age-standardized 5-year net-survivals from Public Health England, for English women with invasive breast cancer diagnosed during 1995-2011 (linked to death certificates, followed through 2016). Piecewise log-linear models with change-point/joinpoint were used to estimate temporal trends. We conducted a quasi-experimental study to test the hypothesis that the trend-change year of proportional incidence coincided with that of 5-year net-survival. Results: Among 254,063 women in England with invasive breast cancer diagnosed during 1995-2011, there was downward-to-upward trend-change in proportional incidence of nonscreened breast cancers (annual percent change[APC]=5.6 after 2007 versus APC=-3.5 before 2007, P<0.001) in diagnosis-year 2007, when steeper upward-trend in age-standardized 5-year net survival started (APC=5.7 after 2007/2008 versus APC=0.3 before 2007/2008, P<0.001).. Net-survival difference of screened versus nonscreened cancers also significantly narrowed (18% in 2007/2008 versus 5% in 2011). Similar associations were found in all strata of race, cancer stage, grade and histology, except in Black patients or patients with stage I, stage III, or grade I cancer. Conclusions: The downward-to-upward trend-change in proportional incidence of nonscreened breast cancers is associated with steeper upward-trend in age-standardized 5-year net survival among English women in recent years. Survival benefits of breast cancer screening appear decreasing in recent years. The data support reduction of breast cancer screening in some patients.

Statistics and pitfalls of trend analysis in cancer research: a review focused on statistical packages

“…For piecewise linear models, the free Joinpoint Regression Program is probably the most user-friendly, yet reasonably functional, statistical package for linear and jointpoint trend-analysis [12,13]. It is capable to compare the trend-slopes and identify the best-fit model for the number and position(s) of the joinpoints (turning-points), by which trend slopes intercept.…”