This major new study confirms that New Zealand’s organised breast screening programme, BreastScreen Aotearoa (BSA) is reducing deaths from breast cancer.
The study concludes that for women who have ever been screened by BSA, the rate of death from breast cancer is reduced by a third, compared to women never screened by the programme.
The study was commissioned by the National Screening Unit and carried out by researchers from the University of New South Wales. The researchers have extensive experience in similar studies, including mortality evaluations of breast screening programmes in Australia.
Results
For New Zealand women overall
New Zealand women who had ever screened in BSA before 2011 were estimated to have:
- 29% lower breast cancer mortality than women never screened, at the average participation rate of 64%
- 34% lower breast cancer mortality than women never screened, using the current participation rate of 71%.
Women who were regular screeners (those who screened three or more times at regular intervals of less than 30 months) compared with never screened women, were estimated to have:
- 33% lower breast cancer mortality at the average participation rate of 64%
- 39% lower breast cancer mortality using the current participation rate of 71%.
Irregular screeners (who had ever screened but did not qualify as regular) were estimated to have:
- 26% lower breast cancer mortality than never screened women at the average participation rate of 64%
- 31% lower breast cancer mortality than never screened women using the current participation rate of 71%.
Māori women
In the inception cohort, adjusted for screening selection bias and age:
- Mâori women who had ever screened in BSA prior to 2011 were estimated to have:
- 17% lower breast cancer mortality than women never screened at the average participation rate of 48%
- 28% lower breast cancer mortality than women never screened using the current Mâori coverage of 65%
- for Mâori women, if a target participation rate of 70% were achieved, it has been estimated that there would be:
- 32% lower breast cancer mortality for women ever screened in BSA compared to women never screened.
Pacific women
These results are from the case-control study, which is not biased by under-reporting of women’s deaths if women return to their home country after diagnosis and treatment.
Pacific women who had ever screened in BSA prior to 2011 were estimated to have:
- 22% lower breast cancer mortality than Pacific women never screened, at the average participation rate of 49%
- 40% lower breast cancer mortality when calculated using more the more recent participation rate of 72%.
For more information
For more information, including a summary and the full report, see the National Screening Unit website.