Assessment of Breast Cancer Mortality Trends Associated With Mammographic Screening and Adjuvant Therapy From 1986 to 2013 in the State of Victoria, Australia
Robert Burton, MD; Christopher Stevenson, PhD
July 26, 2020
Diagnosis of early breast cancer (EBC) in women by mammographic screening and postsurgical adjuvant endocrine therapy and chemotherapy (termed adjuvant therapy  ) began simultaneously in many countries in the 1990s. Subsequent breast cancer mortality declines were variously attributed to mammographic screening and/or adjuvant therapy.
Is population-based mammographic screening or endocrine therapy and chemotherapy (adjuvant therapy) after curative surgery for early or operable breast cancer associated with the decline in breast cancer mortality in Victoria, Australia?
Has the cancer been downstaged thanks to the mammographic screening, explaining the decrease in mortality?
Objective of study
The study presented here was performed in Victoria state, Australia.
The authors are trying to find the link between the reduction in relative mortality with either adjuvant therapy or with screening, and to determine which of these two events would be associated with the observed reduction in mortality in women with early breast cancer who have been subjected to both options (mammography screening and adjuvant treatment after cancer surgery).
This is a cross-sectional analysis  on breast cancer mortality study of 76,630 women registered with invasive breast cancer who completed the screening program and received adjuvant therapy. The population consisted of participants in previous population-based breast cancer studies from 1986 to 2013. Data from 4 population surveys on breast cancer treatment were used from 1986 to 1999.
Comparisons were made between the stages of cancer at the time of diagnosis and the use of adjuvant treatment after surgery.
Advanced breast cancer incidence doubled from 1986 to 2013, and crude breast cancer mortality declined by 30% after 1994; by 1999, most women were receiving adjuvant therapy, which may be associated with this decline.
This analysis of cross-sectional studies showed no downstaging of breast cancer by mammographic screening.
The results indicate that is adjuvant therapy accounted for the observed 30% mortality decline and not the mammogram screening.
Authors suggests that persistence with BreastScreen Victoria may continue to expose Victorian women to unnecessary morbidity and mortality. Given this finding, the authors propose that BreastScreen Victoria program should be terminated. Continuous measurement of breast cancer stages at diagnosis, all-cause and breast cancer–specific mortality, and adjuvant therapy uptake should be mandatory in monitoring and evaluating mammographic screening programs.
1. Treatment that complements a main treatment to prevent the risk of local recurrence or metastases. Chemotherapy, radiotherapy, hormone therapy, immunotherapy may be adjuvant treatments after breast cancer surgery.
2.A cross-sectional analysis is a study which:
-Concerns the population as a whole (as a whole, i.e. it includes all the components of the population, not to be confused with the totality; it is, for the most part only a sample which is studied, but representative of the population as a whole)
-Is performed at a specific point in time (as opposed to longitudinal studies, there is no monitoring of population change over time).