Prospective study of wide local excision and endocrine therapy WithOut RadioTHerapy (WORTH) for node-negative, estrogen receptor-positive early breast cancer with negative histologic margins (WORTH trial, Protocol 1): Three-year interim results

Abstract

615 Background: Although numerous clinical trials have been attempted to categorize breast cancer (BC) subgroups where radiotherapy (RT) to the breast can be abbreviated after breast-conserving surgery (BCS), none have yet realized such subgroups, except for CALGB 9343. However, based on analysis of at 5-mm intervals of the surgical materials in patients (Pts) with complete removal of histologic margins, a Japanese institution has found approximately 1 % annual local recurrence (LR) rate without RT in histologically defined tumor-free tissues 5 mm from the histologic margins. We have conducted a trial to confirm the guidelines of the 5-mm policy in breast conservation without RT using an entry criterion with more stringent screening factors. Methods: We started a prospective trial in Oct. 2002, in which we enrolled the BC Pts after BCS who fulfilled all the following 7 criteria from 13 hospitals, and treated them with tamoxifen or anastrozole alone for 5 years: 1) tumor size of 3 cm or less by palpation; 2) node-negative pathology; 3) without any preoperative treatment; 4) age at operation of 50 years or older and postmenopausal; 5) excised surgical materials were sliced at 5-mm intervals with all slices showing 5-mm tumor free tissues from the margins; 6) histologically without lymphovascular involvement (LI); and 7) with ER-positive tumors. We planned to enroll 120 Pts. The sequential probability ratio test was applied to monitor the annual LR rate would not exceed 1 %. Results: A total of 123 Pts were enrolled in the study, and entry was closed in March 2005. The median age, tumor size (by palpation) and follow-up period were 64 years (range: 51–84), 1.5 cm (range: 0–30) and 36 months (range: 13–58), respectively. Three Pts (0.8 events/100 person-years; 95% CI, 0.26 to 2.51) had LR, and another Pt had distant metastasis. All Pts are alive. Conclusions: Postoperative RT to the breast could be abbreviated in node negative postmenopausal women of 50 years or older with a small (3 cm or less) ER-positive BC showing no LI who had BCS where the surgical materials fulfilled the 5-mm criteria in case where hormone therapy was administered. No significant financial relationships to disclose.