Clinical benefits of using nomogram for predicting positive resection margins in breast conserving surgery

Abstract

Achieving a clear resection margin in breast conserving surgery (BCS) is an important factor in tumor recurrence in breast cancer. To obtain clear resection margins and reduce re-excision rates, some surgeons obtain intraoperative assessments of the margins of excised specimens, using intraoperative frozen biopsy. But intraoperative frozen biopsy has several problems such as low sensitivity or longer operation time. We have previously reported a nomogram for prediction of positive resection margin by integrating preoperatively available clinical and pathologic information. The factors were the presence of microcalcification, mammographic density, tumor size discrepancy between magnetic resonance imaging and ultrasonography, and the presence of ductal carcinoma in situ or lobular carcinoma in needle biopsy specimens. We conducted a prospective trial to examine the accuracy and clinical benefits of the nomogram in 442 breast cancer patients (nomogram group) who underwent BCS between Dec 2011 and March 2013, and compared the clinical outcome with that of the 253 patients (control group) who underwent BCS between Jan 2011 and Oct 2011. For nomogram group, the intraoperative frozen section biopsy was omitted in patients with low nomogram scores. Applying our nomogram did not increase the rate of reoperation due to resection margin positivity when compared to the control group (6.56% vs. 4.25%, respectively, p = 0.22). In the nomogram group, the reoperation rate in patients with low nomogram score who did not undergo intraoperative frozen biopsy was 3.2%, and this is lower than the reoperation rate in the control group. Additionally, we experienced a significant reduction in operation time by 15 minutes when compared to the control group (p<0.001). In conclusion, our results show that out nomogram for predicting positive resection margin for patients who receive BCS can significantly reduce the operation time without increasing reoperation rate.