Abstract PO5-18-03: A Randomized Controlled Trial to Evaluate the Safety and Efficacy of 1 cm versus 2 cm resection margins in Phyllodes Tumours of the Breast - An Exploratory Study

Abstract

Abstract Introduction Phyllodes tumors are rare fibroepithelial tumors constituting 0.3-1% of breast tumors. It presents as a rapidly growing breast lump, with a bosselated surface and overlying shiny stretched skin with dilated prominent veins. Diagnosis is made by mammography and ultrasonography and tissue diagnosis is made by core needle biopsy. The tumor is known for its propensity to grow rapidly within the mesenchymal elements of breast tissue, and to locally recur. Surgery with adequate margins of excision has been known to prevent local recurrence. Phyllodes tumors have inspired much debate among surgeons, regarding the extent of margins during resection. These margins have been defined clearly for carcinoma of the breast (no ink on tumor) but the same consensus has not been reached for Phyllodes tumor. We carried out the world’s first randomized trial to settle the debate to compare the effects of a 1cm margin with that of a 2 cm margin, aiming to arrive at a consensus on the appropriate surgical margin to prevent re-excision and recurrences. We also aimed to compare cosmetic outcomes both subjectively and objectively between the 2 arms. Materials and Methods We carried out a prospective exploratory randomized control trial on patients with suspected phyllodes tumors of the breast from July 2020 to January 2022. After establishing diagnosis, and obtaining informed consent, patients were randomized to either of the 2 arms, to undergo resection with a lcm vs a 2 cm margin. Intraoperatively, the margin of the tumor was delineated by ultrasound for maximum accuracy. The incision made was deepened through the breast and pectoralis major muscle at a distance of exactly 1 cm or 2 cm from the tumor edge. The entire mass was excised en bloc with a 3 dimensional clearance from all sides. If the tumor was found infiltrating the underlying muscle (e.g Pectoralis major muscle, Serratus anterior), a full thickness section of the muscle was also excised with the specimen. The patients were followed up every 3 months with clinical examination and ultrasonography (followed by core needle biopsy for any suspicious mass), for a period of 12-18 months, to evaluate for recurrence.Cosmesis was evaluated by a 5-point Likert scale evaluated by the patient and the surgeon, and objectively using Breast Retraction Assessment and Nipple Deviation. Results We analysed the results of 41 patients who underwent surgery for Phyllodes tumor of the breast. All patients had negative margins after surgery. The mean margin distance (SD) in the 1 cm arm was 0.69 (0.20) cm and 1.83 (0.67) cm in the 2 cm arm. which was statistically significant between the groups. On the follow up ultrasound examination at 12 months, 1 patient (5.3%) was found to have a locoregional recurrence, but this was not statistically significant. There was no statistically significant difference in cosmesis between the arms. Conclusions We achieved our primary objective of histologically negative margins in all patients within both the groups. However, due to the limited number of patients recruited in the study, and due to the short duration of follow-up, we are not able to report significance in terms of recurrences between the 2 groups, to advocate for one over the other. The practice in our unit has been the 2 cm margin, as it offers good oncological outcomes and is definitely safe. Given that cosmetic outcomes were comparable in both arms, one can be assured that a 2 cm margin does not offer worse cosmesis compared to a 1 cm margin. However, our study at this point in time, establishes non inferiority of a 1 cm margin. There have been no randomized control trials conducted in world literature to influence guidelines and clinical practice regarding the ideal margin resection for phyllodes tumor. Our study would be the first of its kind, and is a novel concept not yet conducted for phyllodes tumor. We will continue this trial for years to come, and hope to generate level I data, with increased patient enrolment and a longer duration of follow up. Citation Format: Vandhana Rajgopal, Anita Dhar, Kamal Kataria, Piyush Ranjan, Anurag Srivastava. A Randomized Controlled Trial to Evaluate the Safety and Efficacy of 1 cm versus 2 cm resection margins in Phyllodes Tumours of the Breast - An Exploratory Study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-18-03.