Effect of cavity shaving on reoperation rate following breast-conserving surgery.

Breast-conserving surgery (BCS) without adequate margin clearance carries a high risk of local recurrence. We introduced cavity shaving at primary surgery 31 months ago, to assess tumor margin involvement. The aim of this study was to determine how cavity shaving affects the re-excision rate. We compared a group of 394 patients who underwent BCS with cavity shaving of macroscopically clear margins at primary operation, from March 2003 to September 2005 with a group of 392 patients who underwent BCS only from January 2000 to February 2003. Cavity shaves and re-excision specimens were measured and oriented with reference to the primary cancer. Pathological results of all the specimens were analyzed and re-excision rates in both groups were recorded. Compared with BCS alone where 49 of 392 patients (12.5%) required reoperation for margin clearance, only 22 of 394 patients (5.58%) of the group who had concurrent cavity shaves required further surgery (p < 0.01). Analysis of re-excised specimens suggests that reoperation could have been avoided in 44 of 49 patients, if they had standard sized cavity shave at primary operation. We conclude that cavity shavings during primary BCS significantly reduce the re-excision rate to ensure microscopic clearance.