Abstract
A pilot mammographic breast cancer screening programme was established in 1991 for women aged fifty to sixty-four living in Otago and Southland. The pilot programme was evaluated to measure the acceptability, effectiveness, and economic efficiency of breast cancer screening in New Zealand.
A series of targets related to the performance of the screening programme during its first screening round was used in this evaluation. The targets were derived from screening programmes that had been shown to reduce breast cancer mortality in randomised controlled trials. Methods were developed for measuring these targets in the Otago-Southland pilot programme and the evaluation largely consisted of monitoring these targets, together with carrying out surveys of women in the eligible population and their general practitioners. The results from the evaluation were reported to the programme staff at regular intervals and contributed to the design and management of the pilot programme. Information provided by this evaluation also contributed to the New Zealand government's decision in June 1995, to establish a national breast cancer screening programme which will be implemented over three years.
The early results from the pilot programme were encouraging, with over ninety percent of women aged fifty to sixty-four in Otago and Southland having been identified so they could be invited to be screened. Seventy-four percent of the target population were screened in the first screening round. In the first eighteen months of the programme 7, 182 women were screened. Satisfaction with the screening programme was very high, with ninety-four percent of screened women planning to continue in the programme. As a result of screening 832 women (11.6 percent of those screened) were referred to the assessment clinic. This referral rate did not meet the target that had been set, and as a result the specificity of the programme was low, at eighty-nine percent. Fortunately, despite the high referral rate, few women underwent surgical biopsies and the benign : malignant ratio was excellent, at 0.9 : 1. Breast cancer was diagnosed in seventy-three women; a detection rate of 10.2 per thousand women screened. Sensitivity was excellent, at ninety-two percent. The economic analysis showed that breast cancer screening can be carried out in New Zealand at a similar cost to breast cancer screening programmes in other countries.
The results of the evaluation suggest that the pilot programme will reduce breast cancer mortality, among eligible women, but methods to lower the referral rate and improve specificity should be sought. Arising from the evaluation of the pilot programme, several recommendations are made for implementing a national breast cancer screening programme in New Zealand.