What is achieved by mammographic surveillance after breast conservation treatment for breast cancer?

After breast conservation surgery for breast cancer, patients are followed up by regular clinical examination and mammography, at intervals which vary according to local practice. However, the optimum interval remains unclear with current guidelines suggesting mammography should be carried out every 1 to 2 years. This study has investigated this aspect and, in particular, whether mammography or clinical examination or both allowed an early detection of recurrence of the disease in the conserved breast.

A total of 695 patients who had undergone breast conservation surgery were identified from a database of prospectively recorded data during the period 1990 to 1995. Clinical examination and annual mammography were performed in accordance with local protocol. The results of clinical examination, mammography, and local recurrence rates were evaluated.

A total of 2,181 mammograms were undertaken in the 695 patients studied. Local recurrence of disease in the conserved breast occurred in 21 patients (3%), at a mean follow-up of 3.5 years. The first identification of tumor recurrence was by clinical examination in 11 patients with local recurrence, and by the surveillance mammography in the other 10 patients with local recurrence. Overall, mammography detected the local recurrence in 13 of 20 (65%) patients who underwent this examination. In the other patients, the recurrence was detected on clinical examination only. In addition, in 52 patients, mammography was falsely positive, giving a false positive rate of 2.3%. Contralateral cancers in the opposite breast were detected in 2 patients.

The detection of local disease after breast conservation surgery requires both clinical examination and mammography. In the context of our follow-up policy, in 52% of patients with local recurrence, this was first identified by clinical examination. Disease recurrence was identified in the other 48% of patients by mammographic surveillance. Overall, mammography will identify or confirm local recurrence in two thirds of women. However, in a small number of cases (2.3% in our series) mammography will give false positive results. New imaging modalities to assist in the diagnosis of local recurrence of disease after breast conservation surgery are required.