Re: Effectiveness of and overdiagnosis from mammography screening in the Netherlands: population based study
Evaluation of cancer screening programmes is essential to judge the balance between benefits and harms at the population level. The study by Autier et al. is a contribution to the body of literature evaluating the Dutch breast cancer screening programme. Applying an ecological design to aggregated data on breast cancer mortality is an intuitive approach to study the impact of screening. However, without individual data on screening behaviour and treatment, it is not possible to draw conclusions on the causes of changes in trends in breast cancer mortality. Studies that directly link screening history of eligible women to cause of death can.
For the Dutch screening programme, several studies have shown that women who attend screening halve their change of dying from breast cancer.(1, 2) Taking into consideration the participation rate, several trend studies have shown a consistent association of implementation of screening with time-related changes in breast cancer incidence and mortality in the Netherlands.(3-5) Yet, Autier et al. come to a different conclusion. Apart from the fact that they do not evaluate individual level data including screening invitation and history, an important explanation for this difference is that Autier et al. fail to take an increasing trend in breast cancer incidence into account.
Even though the Netherlands does not have national breast cancer incidence data before the start of screening, it is highly likely that such a trend is present, as also shown in Dutch regions and other countries.(6,7) Assuming that the trend in background incidence can be approximated by the incidence in non-eligible age groups is not sufficient. This explains why in the study by Autier et al. breast cancer mortality reduction, estimated from the advanced cancer rate, is underestimated and overdiagnosis is overestimated, thus distorting the estimated balance between benefits and harms for the Dutch screening programme. The conclusion Autier et al. draw based on an indirect approach to evaluate the impact of screening is therefore misleading. Based on the complete evidence base, also taking into account recent use of adjuvant therapy, screening has been found to substantially reduce breast cancer mortality, in similar amounts as adjuvant therapy.(8) There is no reason to doubt the effectiveness of the Dutch breast cancer screening programme.
References
1. Paap E, Verbeek AL, Botterweck AA, van Doorne-Nagtegaal HJ, Imhof-Tas M, de Koning HJ, Otto SJ, de Munck L, van der Steen A, Holland R, den Heeten GJ, Broeders MJM. Breast cancer screening halves the risk of breast cancer death: A case-referent study. Breast 2014;23:439-44.
2. Otto SJ, Fracheboud J, Verbeek AL, Boer R, Reijerinck-Verheij JC, Otten JD, Broeders MJ, de Koning HJ; for the National Evaluation Team for Breast Cancer Screening. Mammography screening and risk of breast cancer death: a population-based case-control study. Cancer Epidemiol Biomarkers Prev 2012;21:66-73.
3. Sankatsing VDV, van Ravesteyn NT, Heijnsdijk EAM, Looman CWN, van Luijt PA, Fracheboud J, den Heeten GJ, Broeders MJM, de Koning HJ. The effect of population-based mammography screening in Dutch municipalities on breast cancer mortality: 20 years of follow-up. Int J Cancer 2017;141:671-77.
4. Otten JD, Broeders MJ, Fracheboud J, Otto SJ, de Koning HJ, Verbeek AL. Impressive time-related influence of the Dutch screening programme on breast cancer incidence and mortality, 1975-2006. Int J Cancer 2008;123:1929-34.
5. Otto SJ, Fracheboud J, Looman CWN, Broeders MJM, Boer R, Hendriks JHCL, Verbeek ALM, de Koning HJ, and the National Evaluation Team for Breast Cancer Screening. Initiation of population-based mammography screening in Dutch municipalities and effect on breast-cancer mortality: a systematic review. Lancet 2003;361:1411-1417.
6. Louwman WJ, Voogd AC, van Dijck JA, Nieuwenhuijzen GA, Ribot J, Pruijt JF, Coebergh JW. On the rising trends of incidence and prognosis for breast cancer patients diagnosed 1975-2004: a long-term population-based study in southeastern Netherlands. Cancer Causes Control 2008;19:97-106.
7. Botha JL, Bray F, Sankila R, Parkin DM. Breast cancer incidence and mortality trends in 16 European countries. Eur J Cancer 2003 Aug;39(12):1718-29.
8. De Gelder R, Heijnsdijk EA, Fracheboud J, Draisma G, de Koning HJ. The effects of population‐based mammography screening starting between age 40 and 50 in the presence of adjuvant systemic therapy. Int J Cancer 2015;137:165-72.
Competing interests:
No competing interests
14 December 2017
Mireille Broeders
Associate professor
Nicolien van Ravesteyn, Harry de Koning
On behalf of the National Evaluation Team for Breast Cancer Screening
Radboudumc, Nijmegen, and Erasmusmc, Rotterdam, the Netherlands
Rapid Response:
Re: Effectiveness of and overdiagnosis from mammography screening in the Netherlands: population based study
Evaluation of cancer screening programmes is essential to judge the balance between benefits and harms at the population level. The study by Autier et al. is a contribution to the body of literature evaluating the Dutch breast cancer screening programme. Applying an ecological design to aggregated data on breast cancer mortality is an intuitive approach to study the impact of screening. However, without individual data on screening behaviour and treatment, it is not possible to draw conclusions on the causes of changes in trends in breast cancer mortality. Studies that directly link screening history of eligible women to cause of death can.
For the Dutch screening programme, several studies have shown that women who attend screening halve their change of dying from breast cancer.(1, 2) Taking into consideration the participation rate, several trend studies have shown a consistent association of implementation of screening with time-related changes in breast cancer incidence and mortality in the Netherlands.(3-5) Yet, Autier et al. come to a different conclusion. Apart from the fact that they do not evaluate individual level data including screening invitation and history, an important explanation for this difference is that Autier et al. fail to take an increasing trend in breast cancer incidence into account.
Even though the Netherlands does not have national breast cancer incidence data before the start of screening, it is highly likely that such a trend is present, as also shown in Dutch regions and other countries.(6,7) Assuming that the trend in background incidence can be approximated by the incidence in non-eligible age groups is not sufficient. This explains why in the study by Autier et al. breast cancer mortality reduction, estimated from the advanced cancer rate, is underestimated and overdiagnosis is overestimated, thus distorting the estimated balance between benefits and harms for the Dutch screening programme. The conclusion Autier et al. draw based on an indirect approach to evaluate the impact of screening is therefore misleading. Based on the complete evidence base, also taking into account recent use of adjuvant therapy, screening has been found to substantially reduce breast cancer mortality, in similar amounts as adjuvant therapy.(8) There is no reason to doubt the effectiveness of the Dutch breast cancer screening programme.
References
1. Paap E, Verbeek AL, Botterweck AA, van Doorne-Nagtegaal HJ, Imhof-Tas M, de Koning HJ, Otto SJ, de Munck L, van der Steen A, Holland R, den Heeten GJ, Broeders MJM. Breast cancer screening halves the risk of breast cancer death: A case-referent study. Breast 2014;23:439-44.
2. Otto SJ, Fracheboud J, Verbeek AL, Boer R, Reijerinck-Verheij JC, Otten JD, Broeders MJ, de Koning HJ; for the National Evaluation Team for Breast Cancer Screening. Mammography screening and risk of breast cancer death: a population-based case-control study. Cancer Epidemiol Biomarkers Prev 2012;21:66-73.
3. Sankatsing VDV, van Ravesteyn NT, Heijnsdijk EAM, Looman CWN, van Luijt PA, Fracheboud J, den Heeten GJ, Broeders MJM, de Koning HJ. The effect of population-based mammography screening in Dutch municipalities on breast cancer mortality: 20 years of follow-up. Int J Cancer 2017;141:671-77.
4. Otten JD, Broeders MJ, Fracheboud J, Otto SJ, de Koning HJ, Verbeek AL. Impressive time-related influence of the Dutch screening programme on breast cancer incidence and mortality, 1975-2006. Int J Cancer 2008;123:1929-34.
5. Otto SJ, Fracheboud J, Looman CWN, Broeders MJM, Boer R, Hendriks JHCL, Verbeek ALM, de Koning HJ, and the National Evaluation Team for Breast Cancer Screening. Initiation of population-based mammography screening in Dutch municipalities and effect on breast-cancer mortality: a systematic review. Lancet 2003;361:1411-1417.
6. Louwman WJ, Voogd AC, van Dijck JA, Nieuwenhuijzen GA, Ribot J, Pruijt JF, Coebergh JW. On the rising trends of incidence and prognosis for breast cancer patients diagnosed 1975-2004: a long-term population-based study in southeastern Netherlands. Cancer Causes Control 2008;19:97-106.
7. Botha JL, Bray F, Sankila R, Parkin DM. Breast cancer incidence and mortality trends in 16 European countries. Eur J Cancer 2003 Aug;39(12):1718-29.
8. De Gelder R, Heijnsdijk EA, Fracheboud J, Draisma G, de Koning HJ. The effects of population‐based mammography screening starting between age 40 and 50 in the presence of adjuvant systemic therapy. Int J Cancer 2015;137:165-72.
Competing interests: No competing interests