Background: Following treatment for primary breast cancer, annual mammography and regular clinical breast examination is advised. The aim of this study was to investigate whether annual mammography resulted in an improvement in stage of contralateral breast cancers compared with mammography performed at a longer interval.
Methods: This was a retrospective analysis of patients treated for breast cancer, who developed a contralateral breast cancer between 1977 and 1998. Patients were stratified into two groups according to mammographic interval.
Results: Data were available for 275 patients who developed contralateral breast cancer during follow-up. Annual mammography was performed in 51 per cent; these patients were a mean of 5 years younger at diagnosis. Patients who had annual or biennial mammography had comparable rates of impalpable contralateral breast cancer, 30 and 27 per cent respectively. The tumours were of favourable stages in 60 and 58 per cent respectively. Five-year disease-free survival following diagnosis of contralateral breast cancer was 75 per cent in both groups. When the contralateral lesion was detected by mammography, disease-free survival was better, irrespective of the stage of the ipsilateral breast cancer.
Conclusion: No difference was found between the two groups in stage distribution and disease-free survival after the diagnosis of contralateral breast cancer. Survival was better in patients in whom the contralateral breast cancer was first detected by mammography.