Tumour involvement of the re-excision specimen following clear local excision of breast cancer with positive margins

Background: Breast conservation surgery and subsequent radiotherapy is an acceptable method of treating breast cancer. Complete excision of the primary tumour is important to minimize the risk of local recurrence. Re‐excision is usually carried out if the initial primary tumour excision shows positive margins. However, a significant proportion of re‐excision specimens are negative for tumour. The aim of the present study was to identify factors predicting a histologically positive re‐excision specimen. Methods: The case records of all patients with invasive and in situ breast cancer referred to the William Buckland Radiotherapy Centre between January 1996 and December 2001 were reviewed. The factors evaluated were patient age, whether or not tumours were detected by screening mammography, use of hook‐wire needle localization, whether tumours were marked with orientating sutures, histopathological characteristics of the tumour and involvement of axillary nodes. Univariate analysis was performed. Results: In the study period, a total of 1128 patients were reviewed. Of these, 742 underwent breast conservation surgery. Twenty‐nine (3.9%) of the 742 had positive surgical margins and underwent re‐excision. Data were insufficient for six, leaving 23 patients eligible for the study. The number of patients entering the study was small, limiting the statistical analysis. Of these, 21 patients had invasive cancer and two patients had ductal carcinoma in situ only. Of 23 re‐excisions, 11(48%) contained residual tumour. Univariate analysis of the data revealed no significant factors that were likely to predict tumour in the re‐excision specimen. The local recurrence after re‐excision in patients with positive margins was 4.3%. Conclusion: The results suggest that it is not possible to predict which patients will have tumour in the re‐excision specimen. However, approximately 50% of re‐excision specimens showed residual cancer. Therefore it is recommended that all excisions with positive margins need further surgery.