Study designs of evaluations included in the review
Studies with over 100 patients that were published from 1980 onwards were eligible for inclusion. Six studies included in the review were cohort or case-control studies, while in nine the evidence was from expert opinion on the basis of clinical experience, descriptive studies, or reports of expert committees. The authors acknowledged that these studies are vulnerable to important sources of bias.
Specific interventions included in the review
Studies of routine surveillance mammography were eligible for inclusion in the review. The actual mammography regimen used in the included studies varied from twice a year to every 2 years, where reported.
Reference standard test against which the new test was compared
The review did not include any diagnostic accuracy studies that compared the performance of the index test with a reference standard of diagnosis.
Participants included in the review
Patients of any age who had received treatment for primary breast cancer were eligible for inclusion. Patients with ductal carcinoma in situ as their primary diagnosis were excluded from the review. The actual patients included in the review had various stages of disease at initial diagnosis, ranging from benign disease to invasive stage IV disease, where reported. Where stated, the initial treatment that patients had received was a combination of breast-conserving therapy, radiotherapy, chemotherapy and hormone therapy.
Outcomes assessed in the review
Studies measuring the impact of surveillance mammography on disease outcomes were eligible for inclusion. The actual outcomes included in the review were the range and median number of years to recurrence, and the detection rate by mammography alone.
How were decisions on the relevance of primary studies made?
The research team independently reviewed the titles and abstracts of the identified articles to assess their relevance to the review. For those deemed relevant, the full-text article was retrieved and assessed for inclusion based on predefined criteria.