Factors predisposing to cavity margin positivity following conservation surgery for breast cancer

Aims Incomplete excision leads to local recurrence following breast conservation therapy (BCT). The aim of this study was to examine factors associated with cavity margin (CM) positivity and return to theatre rates. Methods Breast conservation surgery with entire CM excision was the initial procedure in 301 patients with 303 breast cancers. Of these, 258 patients were treated successfully with breast conservation surgery and 43 patients subsequently required a mastectomy for persistent involved margins. The mean and median follow-up was 38 and 42 (range 6–78) months, respectively. Results Positive CMs were found in 73 out of 303 tumours. Large tumour size (p<0.001) and tumour type (invasive lobular cancer and ductal carcinoma in-situ) (p=0.043) were significant predictors of CM positivity both by univariate and multivariate analysis. As a result of CM status in relation to initial margin (IM) status, 60 cancers treated that were IM positive but CM negative avoided return for further excision at a second operative procedure. Conclusion Complete CM excision should avoid the need for further re-excision surgery in most patients where initial specimen margin was positive.