The INTEND 1 randomized controlled trial of duct endoscopy as an indicator of margin excision in breast conservation surgery

Purpose With early detection, breast conservation surgery with adequate surgical margins is the standard of care. The aim of this study was to evaluate the use of pre-operative duct endoscopy (DE) to target surgical resection, improve adequate margins and reduce re-excision operations. Methods Women with DCIS, stage I and II breast cancer suitable for breast conservation were randomized to DE-assisted wide local excision versus standard wide local excision (without DE). The primary endpoint was margin re-excision rates between the two groups. Secondary end points were: (i) volume differences of the surgical specimen; (ii) whether an extensive in situ component (EIC) influenced successful DE-guided resection. Results 78 women were randomized: 44 patients to no-DE and 34 patients to the DE group. The median age was 59 (49–65) and 56 (48–64) years in the two groups respectively with mean follow-up of 9.1 (4.2–11.1) years. There were 23 positive findings in 17 women in 30 successful DE procedures (17/30 = 56.7%). The surgical specimen volume, no-DE (17 [IQR 10–29] cm 3 ) and DE 20 [IQR 12–28] cm 3 ), did not differ, p = 0.377. The overall re-excision rate was 20/78 (26%), 9 (20%) and 11 (32% in the no-DE and DE groups, respectively, p = 0.233. Conclusions This randomized clinical trial was limited by incomplete accrual. DE did not contribute to improved margin excision rates whether a target lesion was visualized or not. The presence of EIC did not improve efficacy of DE.