Mammography service screening and breast cancer mortality in New Zealand: a National Cohort Study 1999–2011

Abstract

Background:This breast cancer mortality evaluation of service screening mammography in New Zealand, the first since commencement of screening in 1999, applies to the 1999–2011 diagnostic period. Individual-level linked information on mammography screening, breast cancer diagnosis and breast cancer mortality is used to analyse differences in breast cancer mortality according to participation in organised screening mammography, as provided by BreastScreen Aotearoa (BSA).Methods:Women were followed from the time they became eligible for screening, from age 50 years (1999–2004) and 45 years (⩾2004). Breast cancer mortality from cancers diagnosed during the screening period from 1999 to 2011 (n=4384) is examined in relation to individual screening participation or non-participation during preceding person-years of follow-up from the time of screening eligibility. To account for changes from never- to ever-screened status, breast cancer mortality is calculated for each year in relation to prior accumulated time of participation and non-participation in screening. Breast cancer mortality is also examined in regularly screened women (screened ⩾3 times and mean screening interval ⩽30 months), and irregularly screened women compared with never-screened women. Statistical analyses are by negative binomial and Poisson regression with adjustment for age and ethnic group (Māori, Pacific women) in a repeated-measures analysis. Relative risks for breast cancer mortality compared with never-screened women, are adjusted also for screening selection bias, to indicate the extent of breast cancer mortality reduction in a population offered and not offered mammography screening. Prognostic indicators at diagnosis of breast cancer are also compared between different screening participation groups, including by grade of tumour, extent of disease (spread), multiple tumour status and maximum tumour size using χ2 statistics, t-tests and two-sample median tests.Results:For 1999–2011, after adjusting for age and ethnicity, breast cancer mortality in ever-screened women is estimated to be 62% (95% CI: 51–70) lower than in never-screened women. After further adjustment for screening selection bias, the mortality reduction in NZ is estimated to be 29% (95% CI: 20–38) at an average screening coverage of 64% for 2001–2011, and 34% (95% CI: 25–43) for recent screening coverage (2012–13, 71%). For irregularly screened women, the mortality reduction is estimated to be 31% (95% CI: 21–40), and 39% (95% CI: 22–52) in regularly screened women compared with never-screened women, after adjusting for age, ethnicity and screening selection bias (using recent 2012–2013 screening coverage of 71%). Ever-screened women diagnosed with breast cancer have more favourable prognostic indicators than never-screened women, with a higher proportion of localised cancer (63 compared with 46%), a higher proportion with a well-differentiated tumour (30 compared with 18%), lower risk of multiple tumours (RR=0.48) and smaller median tumour size (15 mm compared with 20 mm)—a...

The incidence of fatal breast cancer measures the increased effectiveness of therapy in women participating in mammography screening

“…For a review of such studies in Europe, see Broeders et al and the recent update of the International Agency for Research on Cancer (IARC) Handbook on Breast Cancer Screening . Substantial reductions in breast cancer mortality with screening have been reported in North America, Asia, Australasia, and elsewhere…”

“…For a review of such studies in Europe, see Broeders et al 17 and the recent update of the International Agency for Research on Cancer (IARC) Handbook on Breast Cancer Screening. 7 Substantial reductions in breast cancer mortality with screening have been reported in North America, 18,19 Asia, 20 Australasia, 21 and elsewhere. 7 Because the majority of women in the population attend some (but not all) of their screening invitations, we have reclassified the individual women in the population each year according to whether or not they participated in their latest screening mammography examination.…”

Gendered and racialized social expectations, barriers, and delayed breast cancer diagnosis

“…4,5 Cancer November 15, 2018 The benefits of screening mammography for women aged 40 years and older have been well documented. 7 The American Joint Committee on Cancer (AJCC) TNM system is often used for breast cancer staging. 6 One of the reasons for the reduction in mortality is due to the early detection of abnormal changes associated with screening mammography.…”

“…6 One of the reasons for the reduction in mortality is due to the early detection of abnormal changes associated with screening mammography. 7 The American Joint Committee on Cancer (AJCC) TNM system is often used for breast cancer staging. 8 A late stage of disease at the time of diagnosis leads to substantially poorer outcomes: the 5-year relative survival rate for women with early-stage disease (stages I and II) is > 90%, whereas the 5-year relative survival rate is approximately 72% for patients with stage III, and only 22% for patients with stage IV breast cancer.…”

Impact of the pink october in the mammographic screening adherence in a reference center in oncology

“…In 2016, there was an estimation of 57,960 new cases of the disease, with an incidence of 56.2 cases every 100 thousand women 2 . Early detection is an important tool for a successful reduction in mortality 3,4 . The method of choice for screening is the mammography.…”