Optimizing surveillance mammography following breast conservation surgery

Prompt detection and treatment of local recurrence (LR) following breast conservation surgery (BCT) may improve subsequent survival. Following early reports demonstrating increased LR in the first years after surgery, a practice of surveillance mammography starting 1 year from diagnosis has become established. Increasing use of adjuvant chemotherapy with adriamycin-containing regimens has resulted in radiotherapy being postponed, so that the first mammogram coincides with the acute radiotherapy reaction, resulting in patient discomfort and poor quality films. We wished to determine if the 1-year mammogram could safely be omitted.

We reviewed 1151 consecutive patients treated with BCT for in situ, stage I or II disease over a 10-year period. All patients had clear resection margins and, where indicated, underwent axillary surgery and adjuvant treatment. This consisted of radiotherapy (40 Gy with a 5 Gy boost), chemotherapy and/or tamoxifen.

Overall, the 5-year actuarial rate of local recurrence was 4.8%. The cumulative risk of LR at 12 months was 0.3% (three patients) and 1.9% (20 patients) at 24 months. This included all cases of high-grade DCIS (>30 mm in size) and all but one tumour with a Nottingham Prognostic index (NPI) of >6.0 which recurred locally.

Even including those patients generally accepted to be at high risk of LR, the cumulative risk of LR was only 0.3% at 12 months from surgery. We now therefore schedule routine biennial mammography from time of surgery except for those with high risk of early local recurrence such as extensive, high-grade in situ disease.