Impact of the suspension and restart of the Dutch breast cancer screening program on breast cancer incidence and stage during the COVID-19 pandemic

Abstract

The COVID-19 pandemic forced the Dutch national breast screening program to a halt in week 12, 2020. In week 26, the breast program was resumed at 40% capacity, which increased to 60% in week 34. We examined the impact of the suspension and restart of the screening program on the incidence of screen-detected and non-screen-detected breast cancer. We selected women aged 50-74, diagnosed during weeks 2-35 of 2018 (n = 7250), 2019 (n = 7302), or 2020 (n = 5306), from the Netherlands Cancer Registry. Weeks 2-35 were divided in seven periods, based on events occurring at the start of the COVID-19 pandemic. Incidence of screen-detected and non-screen-detected tumors was calculated overall and by age group, cT-stage, and cTNM-stage for each period in 2020, and compared to the incidence in the same period of 2018/2019 (averaged). The incidence of screen-detected tumors decreased during weeks 12-13, reached almost zero during weeks 14-25, and increased during weeks 26-35. Incidence of non-screen-detected tumors decreased to a lesser extent during weeks 12-16. The decrease in incidence was seen in all age groups and mainly occurred for cTis, cT1_, DCIS, and stage I tumors. Due to the suspension of the breast cancer screening program, and the restart at reduced capacity, the incidence of screen-detected breast tumors decreased by 67% during weeks 9-35 2020, which equates to about 2000 potentially delayed breast cancer diagnoses. Up to August 2020 there was no indication of a shift towards higher stage breast cancers after restart of the screening.

Keywords: Breast cancer incidence; Breast cancer screening; COVID-19; Clinical tumor stage; cT-stage.

Fig. 1

Division of week 2–35 in seven periods and the corresponding weeks.

Fig. 2

Average weekly incidence, overall (A) and for screen-detected and non-screen-detected tumors (B) separately, per 100.000 women aged 50–74 years living in the Netherlands at the start of the year. The following weeks in 2018 had 4 workings days instead of 5: week 14, 17, 19, and 21. The following weeks in 2019 had 4 working days instead of 5: week 17, 22, and 24. The following weeks in 2020 had 4 working days instead of 5: week 16, 18, 19, 21, and 23.

Fig. 3

Average weekly incidence over two or three weeks, overall (A,B) and for screen-detected (C,D) and non-screen-detected tumors (E,F) separately, per 100.000 women aged 50–74 years, stratified by cT-stage.

Fig. 4

Average weekly incidence over two or three weeks, overall (A,B) and for screen-detected (C,D) and non-screen-detected tumors (E,F) separately, per 100.000 women aged 50–74 years, stratified by cTNM-stage.